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6038f373a3
linux/drivers/gpu/vga/vgaarb.c
Arnd Bergmann 6038f373a3 llseek: automatically add .llseek fop 
All file_operations should get a .llseek operation so we can make
nonseekable_open the default for future file operations without a
.llseek pointer.

The three cases that we can automatically detect are no_llseek, seq_lseek
and default_llseek. For cases where we can we can automatically prove that
the file offset is always ignored, we use noop_llseek, which maintains
the current behavior of not returning an error from a seek.

New drivers should normally not use noop_llseek but instead use no_llseek
and call nonseekable_open at open time.  Existing drivers can be converted
to do the same when the maintainer knows for certain that no user code
relies on calling seek on the device file.

The generated code is often incorrectly indented and right now contains
comments that clarify for each added line why a specific variant was
chosen. In the version that gets submitted upstream, the comments will
be gone and I will manually fix the indentation, because there does not
seem to be a way to do that using coccinelle.

Some amount of new code is currently sitting in linux-next that should get
the same modifications, which I will do at the end of the merge window.

Many thanks to Julia Lawall for helping me learn to write a semantic
patch that does all this.

===== begin semantic patch =====
// This adds an llseek= method to all file operations,
// as a preparation for making no_llseek the default.
//
// The rules are
// - use no_llseek explicitly if we do nonseekable_open
// - use seq_lseek for sequential files
// - use default_llseek if we know we access f_pos
// - use noop_llseek if we know we don't access f_pos,
//   but we still want to allow users to call lseek
//
@ open1 exists @
identifier nested_open;
@@
nested_open(...)
{
<+...
nonseekable_open(...)
...+>
}

@ open exists@
identifier open_f;
identifier i, f;
identifier open1.nested_open;
@@
int open_f(struct inode *i, struct file *f)
{
<+...
(
nonseekable_open(...)
|
nested_open(...)
)
...+>
}

@ read disable optional_qualifier exists @
identifier read_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
expression E;
identifier func;
@@
ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off)
{
<+...
(
   *off = E
|
   *off += E
|
   func(..., off, ...)
|
   E = *off
)
...+>
}

@ read_no_fpos disable optional_qualifier exists @
identifier read_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
@@
ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off)
{
... when != off
}

@ write @
identifier write_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
expression E;
identifier func;
@@
ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off)
{
<+...
(
  *off = E
|
  *off += E
|
  func(..., off, ...)
|
  E = *off
)
...+>
}

@ write_no_fpos @
identifier write_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
@@
ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off)
{
... when != off
}

@ fops0 @
identifier fops;
@@
struct file_operations fops = {
 ...
};

@ has_llseek depends on fops0 @
identifier fops0.fops;
identifier llseek_f;
@@
struct file_operations fops = {
...
 .llseek = llseek_f,
...
};

@ has_read depends on fops0 @
identifier fops0.fops;
identifier read_f;
@@
struct file_operations fops = {
...
 .read = read_f,
...
};

@ has_write depends on fops0 @
identifier fops0.fops;
identifier write_f;
@@
struct file_operations fops = {
...
 .write = write_f,
...
};

@ has_open depends on fops0 @
identifier fops0.fops;
identifier open_f;
@@
struct file_operations fops = {
...
 .open = open_f,
...
};

// use no_llseek if we call nonseekable_open
////////////////////////////////////////////
@ nonseekable1 depends on !has_llseek && has_open @
identifier fops0.fops;
identifier nso ~= "nonseekable_open";
@@
struct file_operations fops = {
...  .open = nso, ...
+.llseek = no_llseek, /* nonseekable */
};

@ nonseekable2 depends on !has_llseek @
identifier fops0.fops;
identifier open.open_f;
@@
struct file_operations fops = {
...  .open = open_f, ...
+.llseek = no_llseek, /* open uses nonseekable */
};

// use seq_lseek for sequential files
/////////////////////////////////////
@ seq depends on !has_llseek @
identifier fops0.fops;
identifier sr ~= "seq_read";
@@
struct file_operations fops = {
...  .read = sr, ...
+.llseek = seq_lseek, /* we have seq_read */
};

// use default_llseek if there is a readdir
///////////////////////////////////////////
@ fops1 depends on !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier readdir_e;
@@
// any other fop is used that changes pos
struct file_operations fops = {
... .readdir = readdir_e, ...
+.llseek = default_llseek, /* readdir is present */
};

// use default_llseek if at least one of read/write touches f_pos
/////////////////////////////////////////////////////////////////
@ fops2 depends on !fops1 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read.read_f;
@@
// read fops use offset
struct file_operations fops = {
... .read = read_f, ...
+.llseek = default_llseek, /* read accesses f_pos */
};

@ fops3 depends on !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier write.write_f;
@@
// write fops use offset
struct file_operations fops = {
... .write = write_f, ...
+	.llseek = default_llseek, /* write accesses f_pos */
};

// Use noop_llseek if neither read nor write accesses f_pos
///////////////////////////////////////////////////////////

@ fops4 depends on !fops1 && !fops2 && !fops3 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read_no_fpos.read_f;
identifier write_no_fpos.write_f;
@@
// write fops use offset
struct file_operations fops = {
...
 .write = write_f,
 .read = read_f,
...
+.llseek = noop_llseek, /* read and write both use no f_pos */
};

@ depends on has_write && !has_read && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier write_no_fpos.write_f;
@@
struct file_operations fops = {
... .write = write_f, ...
+.llseek = noop_llseek, /* write uses no f_pos */
};

@ depends on has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read_no_fpos.read_f;
@@
struct file_operations fops = {
... .read = read_f, ...
+.llseek = noop_llseek, /* read uses no f_pos */
};

@ depends on !has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
@@
struct file_operations fops = {
...
+.llseek = noop_llseek, /* no read or write fn */
};
===== End semantic patch =====

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Julia Lawall <julia@diku.dk>
Cc: Christoph Hellwig <hch@infradead.org>
2010-10-15 15:53:27 +02:00

1244 lines
32 KiB
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/*
* vgaarb.c: Implements the VGA arbitration. For details refer to
* Documentation/vgaarbiter.txt
*
*
* (C) Copyright 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org>
* (C) Copyright 2007 Paulo R. Zanoni <przanoni@gmail.com>
* (C) Copyright 2007, 2009 Tiago Vignatti <vignatti@freedesktop.org>
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS
* IN THE SOFTWARE.
*
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/pci.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/spinlock.h>
#include <linux/poll.h>
#include <linux/miscdevice.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/vgaarb.h>
static void vga_arbiter_notify_clients(void);
/*
* We keep a list of all vga devices in the system to speed
* up the various operations of the arbiter
*/
struct vga_device {
struct list_head list;
struct pci_dev *pdev;
unsigned int decodes; /* what does it decodes */
unsigned int owns; /* what does it owns */
unsigned int locks; /* what does it locks */
unsigned int io_lock_cnt; /* legacy IO lock count */
unsigned int mem_lock_cnt; /* legacy MEM lock count */
unsigned int io_norm_cnt; /* normal IO count */
unsigned int mem_norm_cnt; /* normal MEM count */
/* allow IRQ enable/disable hook */
void *cookie;
void (*irq_set_state)(void *cookie, bool enable);
unsigned int (*set_vga_decode)(void *cookie, bool decode);
};
static LIST_HEAD(vga_list);
static int vga_count, vga_decode_count;
static bool vga_arbiter_used;
static DEFINE_SPINLOCK(vga_lock);
static DECLARE_WAIT_QUEUE_HEAD(vga_wait_queue);
static const char *vga_iostate_to_str(unsigned int iostate)
{
/* Ignore VGA_RSRC_IO and VGA_RSRC_MEM */
iostate &= VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
switch (iostate) {
case VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM:
return "io+mem";
case VGA_RSRC_LEGACY_IO:
return "io";
case VGA_RSRC_LEGACY_MEM:
return "mem";
}
return "none";
}
static int vga_str_to_iostate(char *buf, int str_size, int *io_state)
{
/* we could in theory hand out locks on IO and mem
* separately to userspace but it can cause deadlocks */
if (strncmp(buf, "none", 4) == 0) {
*io_state = VGA_RSRC_NONE;
return 1;
}
/* XXX We're not chekcing the str_size! */
if (strncmp(buf, "io+mem", 6) == 0)
goto both;
else if (strncmp(buf, "io", 2) == 0)
goto both;
else if (strncmp(buf, "mem", 3) == 0)
goto both;
return 0;
both:
*io_state = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
return 1;
}
#ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
/* this is only used a cookie - it should not be dereferenced */
static struct pci_dev *vga_default;
#endif
static void vga_arb_device_card_gone(struct pci_dev *pdev);
/* Find somebody in our list */
static struct vga_device *vgadev_find(struct pci_dev *pdev)
{
struct vga_device *vgadev;
list_for_each_entry(vgadev, &vga_list, list)
if (pdev == vgadev->pdev)
return vgadev;
return NULL;
}
/* Returns the default VGA device (vgacon's babe) */
#ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
struct pci_dev *vga_default_device(void)
{
return vga_default;
}
#endif
static inline void vga_irq_set_state(struct vga_device *vgadev, bool state)
{
if (vgadev->irq_set_state)
vgadev->irq_set_state(vgadev->cookie, state);
}
/* If we don't ever use VGA arb we should avoid
turning off anything anywhere due to old X servers getting
confused about the boot device not being VGA */
static void vga_check_first_use(void)
{
/* we should inform all GPUs in the system that
* VGA arb has occured and to try and disable resources
* if they can */
if (!vga_arbiter_used) {
vga_arbiter_used = true;
vga_arbiter_notify_clients();
}
}
static struct vga_device *__vga_tryget(struct vga_device *vgadev,
unsigned int rsrc)
{
unsigned int wants, legacy_wants, match;
struct vga_device *conflict;
unsigned int pci_bits;
/* Account for "normal" resources to lock. If we decode the legacy,
* counterpart, we need to request it as well
*/
if ((rsrc & VGA_RSRC_NORMAL_IO) &&
(vgadev->decodes & VGA_RSRC_LEGACY_IO))
rsrc |= VGA_RSRC_LEGACY_IO;
if ((rsrc & VGA_RSRC_NORMAL_MEM) &&
(vgadev->decodes & VGA_RSRC_LEGACY_MEM))
rsrc |= VGA_RSRC_LEGACY_MEM;
pr_debug("%s: %d\n", __func__, rsrc);
pr_debug("%s: owns: %d\n", __func__, vgadev->owns);
/* Check what resources we need to acquire */
wants = rsrc & ~vgadev->owns;
/* We already own everything, just mark locked & bye bye */
if (wants == 0)
goto lock_them;
/* We don't need to request a legacy resource, we just enable
* appropriate decoding and go
*/
legacy_wants = wants & VGA_RSRC_LEGACY_MASK;
if (legacy_wants == 0)
goto enable_them;
/* Ok, we don't, let's find out how we need to kick off */
list_for_each_entry(conflict, &vga_list, list) {
unsigned int lwants = legacy_wants;
unsigned int change_bridge = 0;
/* Don't conflict with myself */
if (vgadev == conflict)
continue;
/* Check if the architecture allows a conflict between those
* 2 devices or if they are on separate domains
*/
if (!vga_conflicts(vgadev->pdev, conflict->pdev))
continue;
/* We have a possible conflict. before we go further, we must
* check if we sit on the same bus as the conflicting device.
* if we don't, then we must tie both IO and MEM resources
* together since there is only a single bit controlling
* VGA forwarding on P2P bridges
*/
if (vgadev->pdev->bus != conflict->pdev->bus) {
change_bridge = 1;
lwants = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
}
/* Check if the guy has a lock on the resource. If he does,
* return the conflicting entry
*/
if (conflict->locks & lwants)
return conflict;
/* Ok, now check if he owns the resource we want. We don't need
* to check "decodes" since it should be impossible to own
* own legacy resources you don't decode unless I have a bug
* in this code...
*/
WARN_ON(conflict->owns & ~conflict->decodes);
match = lwants & conflict->owns;
if (!match)
continue;
/* looks like he doesn't have a lock, we can steal
* them from him
*/
vga_irq_set_state(conflict, false);
pci_bits = 0;
if (lwants & (VGA_RSRC_LEGACY_MEM|VGA_RSRC_NORMAL_MEM))
pci_bits |= PCI_COMMAND_MEMORY;
if (lwants & (VGA_RSRC_LEGACY_IO|VGA_RSRC_NORMAL_IO))
pci_bits |= PCI_COMMAND_IO;
pci_set_vga_state(conflict->pdev, false, pci_bits,
change_bridge);
conflict->owns &= ~lwants;
/* If he also owned non-legacy, that is no longer the case */
if (lwants & VGA_RSRC_LEGACY_MEM)
conflict->owns &= ~VGA_RSRC_NORMAL_MEM;
if (lwants & VGA_RSRC_LEGACY_IO)
conflict->owns &= ~VGA_RSRC_NORMAL_IO;
}
enable_them:
/* ok dude, we got it, everybody conflicting has been disabled, let's
* enable us. Make sure we don't mark a bit in "owns" that we don't
* also have in "decodes". We can lock resources we don't decode but
* not own them.
*/
pci_bits = 0;
if (wants & (VGA_RSRC_LEGACY_MEM|VGA_RSRC_NORMAL_MEM))
pci_bits |= PCI_COMMAND_MEMORY;
if (wants & (VGA_RSRC_LEGACY_IO|VGA_RSRC_NORMAL_IO))
pci_bits |= PCI_COMMAND_IO;
pci_set_vga_state(vgadev->pdev, true, pci_bits, !!(wants & VGA_RSRC_LEGACY_MASK));
vga_irq_set_state(vgadev, true);
vgadev->owns |= (wants & vgadev->decodes);
lock_them:
vgadev->locks |= (rsrc & VGA_RSRC_LEGACY_MASK);
if (rsrc & VGA_RSRC_LEGACY_IO)
vgadev->io_lock_cnt++;
if (rsrc & VGA_RSRC_LEGACY_MEM)
vgadev->mem_lock_cnt++;
if (rsrc & VGA_RSRC_NORMAL_IO)
vgadev->io_norm_cnt++;
if (rsrc & VGA_RSRC_NORMAL_MEM)
vgadev->mem_norm_cnt++;
return NULL;
}
static void __vga_put(struct vga_device *vgadev, unsigned int rsrc)
{
unsigned int old_locks = vgadev->locks;
pr_debug("%s\n", __func__);
/* Update our counters, and account for equivalent legacy resources
* if we decode them
*/
if ((rsrc & VGA_RSRC_NORMAL_IO) && vgadev->io_norm_cnt > 0) {
vgadev->io_norm_cnt--;
if (vgadev->decodes & VGA_RSRC_LEGACY_IO)
rsrc |= VGA_RSRC_LEGACY_IO;
}
if ((rsrc & VGA_RSRC_NORMAL_MEM) && vgadev->mem_norm_cnt > 0) {
vgadev->mem_norm_cnt--;
if (vgadev->decodes & VGA_RSRC_LEGACY_MEM)
rsrc |= VGA_RSRC_LEGACY_MEM;
}
if ((rsrc & VGA_RSRC_LEGACY_IO) && vgadev->io_lock_cnt > 0)
vgadev->io_lock_cnt--;
if ((rsrc & VGA_RSRC_LEGACY_MEM) && vgadev->mem_lock_cnt > 0)
vgadev->mem_lock_cnt--;
/* Just clear lock bits, we do lazy operations so we don't really
* have to bother about anything else at this point
*/
if (vgadev->io_lock_cnt == 0)
vgadev->locks &= ~VGA_RSRC_LEGACY_IO;
if (vgadev->mem_lock_cnt == 0)
vgadev->locks &= ~VGA_RSRC_LEGACY_MEM;
/* Kick the wait queue in case somebody was waiting if we actually
* released something
*/
if (old_locks != vgadev->locks)
wake_up_all(&vga_wait_queue);
}
int vga_get(struct pci_dev *pdev, unsigned int rsrc, int interruptible)
{
struct vga_device *vgadev, *conflict;
unsigned long flags;
wait_queue_t wait;
int rc = 0;
vga_check_first_use();
/* The one who calls us should check for this, but lets be sure... */
if (pdev == NULL)
pdev = vga_default_device();
if (pdev == NULL)
return 0;
for (;;) {
spin_lock_irqsave(&vga_lock, flags);
vgadev = vgadev_find(pdev);
if (vgadev == NULL) {
spin_unlock_irqrestore(&vga_lock, flags);
rc = -ENODEV;
break;
}
conflict = __vga_tryget(vgadev, rsrc);
spin_unlock_irqrestore(&vga_lock, flags);
if (conflict == NULL)
break;
/* We have a conflict, we wait until somebody kicks the
* work queue. Currently we have one work queue that we
* kick each time some resources are released, but it would
* be fairly easy to have a per device one so that we only
* need to attach to the conflicting device
*/
init_waitqueue_entry(&wait, current);
add_wait_queue(&vga_wait_queue, &wait);
set_current_state(interruptible ?
TASK_INTERRUPTIBLE :
TASK_UNINTERRUPTIBLE);
if (signal_pending(current)) {
rc = -EINTR;
break;
}
schedule();
remove_wait_queue(&vga_wait_queue, &wait);
set_current_state(TASK_RUNNING);
}
return rc;
}
EXPORT_SYMBOL(vga_get);
int vga_tryget(struct pci_dev *pdev, unsigned int rsrc)
{
struct vga_device *vgadev;
unsigned long flags;
int rc = 0;
vga_check_first_use();
/* The one who calls us should check for this, but lets be sure... */
if (pdev == NULL)
pdev = vga_default_device();
if (pdev == NULL)
return 0;
spin_lock_irqsave(&vga_lock, flags);
vgadev = vgadev_find(pdev);
if (vgadev == NULL) {
rc = -ENODEV;
goto bail;
}
if (__vga_tryget(vgadev, rsrc))
rc = -EBUSY;
bail:
spin_unlock_irqrestore(&vga_lock, flags);
return rc;
}
EXPORT_SYMBOL(vga_tryget);
void vga_put(struct pci_dev *pdev, unsigned int rsrc)
{
struct vga_device *vgadev;
unsigned long flags;
/* The one who calls us should check for this, but lets be sure... */
if (pdev == NULL)
pdev = vga_default_device();
if (pdev == NULL)
return;
spin_lock_irqsave(&vga_lock, flags);
vgadev = vgadev_find(pdev);
if (vgadev == NULL)
goto bail;
__vga_put(vgadev, rsrc);
bail:
spin_unlock_irqrestore(&vga_lock, flags);
}
EXPORT_SYMBOL(vga_put);
/*
* Currently, we assume that the "initial" setup of the system is
* not sane, that is we come up with conflicting devices and let
* the arbiter's client decides if devices decodes or not legacy
* things.
*/
static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
{
struct vga_device *vgadev;
unsigned long flags;
struct pci_bus *bus;
struct pci_dev *bridge;
u16 cmd;
/* Only deal with VGA class devices */
if ((pdev->class >> 8) != PCI_CLASS_DISPLAY_VGA)
return false;
/* Allocate structure */
vgadev = kmalloc(sizeof(struct vga_device), GFP_KERNEL);
if (vgadev == NULL) {
pr_err("vgaarb: failed to allocate pci device\n");
/* What to do on allocation failure ? For now, let's
* just do nothing, I'm not sure there is anything saner
* to be done
*/
return false;
}
memset(vgadev, 0, sizeof(*vgadev));
/* Take lock & check for duplicates */
spin_lock_irqsave(&vga_lock, flags);
if (vgadev_find(pdev) != NULL) {
BUG_ON(1);
goto fail;
}
vgadev->pdev = pdev;
/* By default, assume we decode everything */
vgadev->decodes = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM |
VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
/* by default mark it as decoding */
vga_decode_count++;
/* Mark that we "own" resources based on our enables, we will
* clear that below if the bridge isn't forwarding
*/
pci_read_config_word(pdev, PCI_COMMAND, &cmd);
if (cmd & PCI_COMMAND_IO)
vgadev->owns |= VGA_RSRC_LEGACY_IO;
if (cmd & PCI_COMMAND_MEMORY)
vgadev->owns |= VGA_RSRC_LEGACY_MEM;
/* Check if VGA cycles can get down to us */
bus = pdev->bus;
while (bus) {
bridge = bus->self;
if (bridge) {
u16 l;
pci_read_config_word(bridge, PCI_BRIDGE_CONTROL,
&l);
if (!(l & PCI_BRIDGE_CTL_VGA)) {
vgadev->owns = 0;
break;
}
}
bus = bus->parent;
}
/* Deal with VGA default device. Use first enabled one
* by default if arch doesn't have it's own hook
*/
#ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
if (vga_default == NULL &&
((vgadev->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK))
vga_default = pci_dev_get(pdev);
#endif
/* Add to the list */
list_add(&vgadev->list, &vga_list);
vga_count++;
pr_info("vgaarb: device added: PCI:%s,decodes=%s,owns=%s,locks=%s\n",
pci_name(pdev),
vga_iostate_to_str(vgadev->decodes),
vga_iostate_to_str(vgadev->owns),
vga_iostate_to_str(vgadev->locks));
spin_unlock_irqrestore(&vga_lock, flags);
return true;
fail:
spin_unlock_irqrestore(&vga_lock, flags);
kfree(vgadev);
return false;
}
static bool vga_arbiter_del_pci_device(struct pci_dev *pdev)
{
struct vga_device *vgadev;
unsigned long flags;
bool ret = true;
spin_lock_irqsave(&vga_lock, flags);
vgadev = vgadev_find(pdev);
if (vgadev == NULL) {
ret = false;
goto bail;
}
if (vga_default == pdev) {
pci_dev_put(vga_default);
vga_default = NULL;
}
if (vgadev->decodes & (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM))
vga_decode_count--;
/* Remove entry from list */
list_del(&vgadev->list);
vga_count--;
/* Notify userland driver that the device is gone so it discards
* it's copies of the pci_dev pointer
*/
vga_arb_device_card_gone(pdev);
/* Wake up all possible waiters */
wake_up_all(&vga_wait_queue);
bail:
spin_unlock_irqrestore(&vga_lock, flags);
kfree(vgadev);
return ret;
}
/* this is called with the lock */
static inline void vga_update_device_decodes(struct vga_device *vgadev,
int new_decodes)
{
int old_decodes;
struct vga_device *new_vgadev, *conflict;
old_decodes = vgadev->decodes;
vgadev->decodes = new_decodes;
pr_info("vgaarb: device changed decodes: PCI:%s,olddecodes=%s,decodes=%s:owns=%s\n",
pci_name(vgadev->pdev),
vga_iostate_to_str(old_decodes),
vga_iostate_to_str(vgadev->decodes),
vga_iostate_to_str(vgadev->owns));
/* if we own the decodes we should move them along to
another card */
if ((vgadev->owns & old_decodes) && (vga_count > 1)) {
/* set us to own nothing */
vgadev->owns &= ~old_decodes;
list_for_each_entry(new_vgadev, &vga_list, list) {
if ((new_vgadev != vgadev) &&
(new_vgadev->decodes & VGA_RSRC_LEGACY_MASK)) {
pr_info("vgaarb: transferring owner from PCI:%s to PCI:%s\n", pci_name(vgadev->pdev), pci_name(new_vgadev->pdev));
conflict = __vga_tryget(new_vgadev, VGA_RSRC_LEGACY_MASK);
if (!conflict)
__vga_put(new_vgadev, VGA_RSRC_LEGACY_MASK);
break;
}
}
}
/* change decodes counter */
if (old_decodes != new_decodes) {
if (new_decodes & (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM))
vga_decode_count++;
else
vga_decode_count--;
}
pr_debug("vgaarb: decoding count now is: %d\n", vga_decode_count);
}
void __vga_set_legacy_decoding(struct pci_dev *pdev, unsigned int decodes, bool userspace)
{
struct vga_device *vgadev;
unsigned long flags;
decodes &= VGA_RSRC_LEGACY_MASK;
spin_lock_irqsave(&vga_lock, flags);
vgadev = vgadev_find(pdev);
if (vgadev == NULL)
goto bail;
/* don't let userspace futz with kernel driver decodes */
if (userspace && vgadev->set_vga_decode)
goto bail;
/* update the device decodes + counter */
vga_update_device_decodes(vgadev, decodes);
/* XXX if somebody is going from "doesn't decode" to "decodes" state
* here, additional care must be taken as we may have pending owner
* ship of non-legacy region ...
*/
bail:
spin_unlock_irqrestore(&vga_lock, flags);
}
void vga_set_legacy_decoding(struct pci_dev *pdev, unsigned int decodes)
{
__vga_set_legacy_decoding(pdev, decodes, false);
}
EXPORT_SYMBOL(vga_set_legacy_decoding);
/* call with NULL to unregister */
int vga_client_register(struct pci_dev *pdev, void *cookie,
void (*irq_set_state)(void *cookie, bool state),
unsigned int (*set_vga_decode)(void *cookie, bool decode))
{
int ret = -1;
struct vga_device *vgadev;
unsigned long flags;
spin_lock_irqsave(&vga_lock, flags);
vgadev = vgadev_find(pdev);
if (!vgadev)
goto bail;
vgadev->irq_set_state = irq_set_state;
vgadev->set_vga_decode = set_vga_decode;
vgadev->cookie = cookie;
ret = 0;
bail:
spin_unlock_irqrestore(&vga_lock, flags);
return ret;
}
EXPORT_SYMBOL(vga_client_register);
/*
* Char driver implementation
*
* Semantics is:
*
* open : open user instance of the arbitrer. by default, it's
* attached to the default VGA device of the system.
*
* close : close user instance, release locks
*
* read : return a string indicating the status of the target.
* an IO state string is of the form {io,mem,io+mem,none},
* mc and ic are respectively mem and io lock counts (for
* debugging/diagnostic only). "decodes" indicate what the
* card currently decodes, "owns" indicates what is currently
* enabled on it, and "locks" indicates what is locked by this
* card. If the card is unplugged, we get "invalid" then for
* card_ID and an -ENODEV error is returned for any command
* until a new card is targeted
*
* "<card_ID>,decodes=<io_state>,owns=<io_state>,locks=<io_state> (ic,mc)"
*
* write : write a command to the arbiter. List of commands is:
*
* target <card_ID> : switch target to card <card_ID> (see below)
* lock <io_state> : acquires locks on target ("none" is invalid io_state)
* trylock <io_state> : non-blocking acquire locks on target
* unlock <io_state> : release locks on target
* unlock all : release all locks on target held by this user
* decodes <io_state> : set the legacy decoding attributes for the card
*
* poll : event if something change on any card (not just the target)
*
* card_ID is of the form "PCI:domain:bus:dev.fn". It can be set to "default"
* to go back to the system default card (TODO: not implemented yet).
* Currently, only PCI is supported as a prefix, but the userland API may
* support other bus types in the future, even if the current kernel
* implementation doesn't.
*
* Note about locks:
*
* The driver keeps track of which user has what locks on which card. It
* supports stacking, like the kernel one. This complexifies the implementation
* a bit, but makes the arbiter more tolerant to userspace problems and able
* to properly cleanup in all cases when a process dies.
* Currently, a max of 16 cards simultaneously can have locks issued from
* userspace for a given user (file descriptor instance) of the arbiter.
*
* If the device is hot-unplugged, there is a hook inside the module to notify
* they being added/removed in the system and automatically added/removed in
* the arbiter.
*/
#define MAX_USER_CARDS CONFIG_VGA_ARB_MAX_GPUS
#define PCI_INVALID_CARD ((struct pci_dev *)-1UL)
/*
* Each user has an array of these, tracking which cards have locks
*/
struct vga_arb_user_card {
struct pci_dev *pdev;
unsigned int mem_cnt;
unsigned int io_cnt;
};
struct vga_arb_private {
struct list_head list;
struct pci_dev *target;
struct vga_arb_user_card cards[MAX_USER_CARDS];
spinlock_t lock;
};
static LIST_HEAD(vga_user_list);
static DEFINE_SPINLOCK(vga_user_lock);
/*
* This function gets a string in the format: "PCI:domain:bus:dev.fn" and
* returns the respective values. If the string is not in this format,
* it returns 0.
*/
static int vga_pci_str_to_vars(char *buf, int count, unsigned int *domain,
unsigned int *bus, unsigned int *devfn)
{
int n;
unsigned int slot, func;
n = sscanf(buf, "PCI:%x:%x:%x.%x", domain, bus, &slot, &func);
if (n != 4)
return 0;
*devfn = PCI_DEVFN(slot, func);
return 1;
}
static ssize_t vga_arb_read(struct file *file, char __user * buf,
size_t count, loff_t *ppos)
{
struct vga_arb_private *priv = file->private_data;
struct vga_device *vgadev;
struct pci_dev *pdev;
unsigned long flags;
size_t len;
int rc;
char *lbuf;
lbuf = kmalloc(1024, GFP_KERNEL);
if (lbuf == NULL)
return -ENOMEM;
/* Shields against vga_arb_device_card_gone (pci_dev going
* away), and allows access to vga list
*/
spin_lock_irqsave(&vga_lock, flags);
/* If we are targetting the default, use it */
pdev = priv->target;
if (pdev == NULL || pdev == PCI_INVALID_CARD) {
spin_unlock_irqrestore(&vga_lock, flags);
len = sprintf(lbuf, "invalid");
goto done;
}
/* Find card vgadev structure */
vgadev = vgadev_find(pdev);
if (vgadev == NULL) {
/* Wow, it's not in the list, that shouldn't happen,
* let's fix us up and return invalid card
*/
if (pdev == priv->target)
vga_arb_device_card_gone(pdev);
spin_unlock_irqrestore(&vga_lock, flags);
len = sprintf(lbuf, "invalid");
goto done;
}
/* Fill the buffer with infos */
len = snprintf(lbuf, 1024,
"count:%d,PCI:%s,decodes=%s,owns=%s,locks=%s(%d:%d)\n",
vga_decode_count, pci_name(pdev),
vga_iostate_to_str(vgadev->decodes),
vga_iostate_to_str(vgadev->owns),
vga_iostate_to_str(vgadev->locks),
vgadev->io_lock_cnt, vgadev->mem_lock_cnt);
spin_unlock_irqrestore(&vga_lock, flags);
done:
/* Copy that to user */
if (len > count)
len = count;
rc = copy_to_user(buf, lbuf, len);
kfree(lbuf);
if (rc)
return -EFAULT;
return len;
}
/*
* TODO: To avoid parsing inside kernel and to improve the speed we may
* consider use ioctl here
*/
static ssize_t vga_arb_write(struct file *file, const char __user * buf,
size_t count, loff_t *ppos)
{
struct vga_arb_private *priv = file->private_data;
struct vga_arb_user_card *uc = NULL;
struct pci_dev *pdev;
unsigned int io_state;
char *kbuf, *curr_pos;
size_t remaining = count;
int ret_val;
int i;
kbuf = kmalloc(count + 1, GFP_KERNEL);
if (!kbuf)
return -ENOMEM;
if (copy_from_user(kbuf, buf, count)) {
kfree(kbuf);
return -EFAULT;
}
curr_pos = kbuf;
kbuf[count] = '\0'; /* Just to make sure... */
if (strncmp(curr_pos, "lock ", 5) == 0) {
curr_pos += 5;
remaining -= 5;
pr_debug("client 0x%p called 'lock'\n", priv);
if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
ret_val = -EPROTO;
goto done;
}
if (io_state == VGA_RSRC_NONE) {
ret_val = -EPROTO;
goto done;
}
pdev = priv->target;
if (priv->target == NULL) {
ret_val = -ENODEV;
goto done;
}
vga_get_uninterruptible(pdev, io_state);
/* Update the client's locks lists... */
for (i = 0; i < MAX_USER_CARDS; i++) {
if (priv->cards[i].pdev == pdev) {
if (io_state & VGA_RSRC_LEGACY_IO)
priv->cards[i].io_cnt++;
if (io_state & VGA_RSRC_LEGACY_MEM)
priv->cards[i].mem_cnt++;
break;
}
}
ret_val = count;
goto done;
} else if (strncmp(curr_pos, "unlock ", 7) == 0) {
curr_pos += 7;
remaining -= 7;
pr_debug("client 0x%p called 'unlock'\n", priv);
if (strncmp(curr_pos, "all", 3) == 0)
io_state = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
else {
if (!vga_str_to_iostate
(curr_pos, remaining, &io_state)) {
ret_val = -EPROTO;
goto done;
}
/* TODO: Add this?
if (io_state == VGA_RSRC_NONE) {
ret_val = -EPROTO;
goto done;
}
*/
}
pdev = priv->target;
if (priv->target == NULL) {
ret_val = -ENODEV;
goto done;
}
for (i = 0; i < MAX_USER_CARDS; i++) {
if (priv->cards[i].pdev == pdev)
uc = &priv->cards[i];
}
if (!uc)
return -EINVAL;
if (io_state & VGA_RSRC_LEGACY_IO && uc->io_cnt == 0)
return -EINVAL;
if (io_state & VGA_RSRC_LEGACY_MEM && uc->mem_cnt == 0)
return -EINVAL;
vga_put(pdev, io_state);
if (io_state & VGA_RSRC_LEGACY_IO)
uc->io_cnt--;
if (io_state & VGA_RSRC_LEGACY_MEM)
uc->mem_cnt--;
ret_val = count;
goto done;
} else if (strncmp(curr_pos, "trylock ", 8) == 0) {
curr_pos += 8;
remaining -= 8;
pr_debug("client 0x%p called 'trylock'\n", priv);
if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
ret_val = -EPROTO;
goto done;
}
/* TODO: Add this?
if (io_state == VGA_RSRC_NONE) {
ret_val = -EPROTO;
goto done;
}
*/
pdev = priv->target;
if (priv->target == NULL) {
ret_val = -ENODEV;
goto done;
}
if (vga_tryget(pdev, io_state)) {
/* Update the client's locks lists... */
for (i = 0; i < MAX_USER_CARDS; i++) {
if (priv->cards[i].pdev == pdev) {
if (io_state & VGA_RSRC_LEGACY_IO)
priv->cards[i].io_cnt++;
if (io_state & VGA_RSRC_LEGACY_MEM)
priv->cards[i].mem_cnt++;
break;
}
}
ret_val = count;
goto done;
} else {
ret_val = -EBUSY;
goto done;
}
} else if (strncmp(curr_pos, "target ", 7) == 0) {
struct pci_bus *pbus;
unsigned int domain, bus, devfn;
struct vga_device *vgadev;
curr_pos += 7;
remaining -= 7;
pr_debug("client 0x%p called 'target'\n", priv);
/* if target is default */
if (!strncmp(curr_pos, "default", 7))
pdev = pci_dev_get(vga_default_device());
else {
if (!vga_pci_str_to_vars(curr_pos, remaining,
&domain, &bus, &devfn)) {
ret_val = -EPROTO;
goto done;
}
pr_debug("vgaarb: %s ==> %x:%x:%x.%x\n", curr_pos,
domain, bus, PCI_SLOT(devfn), PCI_FUNC(devfn));
pbus = pci_find_bus(domain, bus);
pr_debug("vgaarb: pbus %p\n", pbus);
if (pbus == NULL) {
pr_err("vgaarb: invalid PCI domain and/or bus address %x:%x\n",
domain, bus);
ret_val = -ENODEV;
goto done;
}
pdev = pci_get_slot(pbus, devfn);
pr_debug("vgaarb: pdev %p\n", pdev);
if (!pdev) {
pr_err("vgaarb: invalid PCI address %x:%x\n",
bus, devfn);
ret_val = -ENODEV;
goto done;
}
}
vgadev = vgadev_find(pdev);
pr_debug("vgaarb: vgadev %p\n", vgadev);
if (vgadev == NULL) {
pr_err("vgaarb: this pci device is not a vga device\n");
pci_dev_put(pdev);
ret_val = -ENODEV;
goto done;
}
priv->target = pdev;
for (i = 0; i < MAX_USER_CARDS; i++) {
if (priv->cards[i].pdev == pdev)
break;
if (priv->cards[i].pdev == NULL) {
priv->cards[i].pdev = pdev;
priv->cards[i].io_cnt = 0;
priv->cards[i].mem_cnt = 0;
break;
}
}
if (i == MAX_USER_CARDS) {
pr_err("vgaarb: maximum user cards (%d) number reached!\n",
MAX_USER_CARDS);
pci_dev_put(pdev);
/* XXX: which value to return? */
ret_val = -ENOMEM;
goto done;
}
ret_val = count;
pci_dev_put(pdev);
goto done;
} else if (strncmp(curr_pos, "decodes ", 8) == 0) {
curr_pos += 8;
remaining -= 8;
pr_debug("vgaarb: client 0x%p called 'decodes'\n", priv);
if (!vga_str_to_iostate(curr_pos, remaining, &io_state)) {
ret_val = -EPROTO;
goto done;
}
pdev = priv->target;
if (priv->target == NULL) {
ret_val = -ENODEV;
goto done;
}
__vga_set_legacy_decoding(pdev, io_state, true);
ret_val = count;
goto done;
}
/* If we got here, the message written is not part of the protocol! */
kfree(kbuf);
return -EPROTO;
done:
kfree(kbuf);
return ret_val;
}
static unsigned int vga_arb_fpoll(struct file *file, poll_table * wait)
{
struct vga_arb_private *priv = file->private_data;
pr_debug("%s\n", __func__);
if (priv == NULL)
return -ENODEV;
poll_wait(file, &vga_wait_queue, wait);
return POLLIN;
}
static int vga_arb_open(struct inode *inode, struct file *file)
{
struct vga_arb_private *priv;
unsigned long flags;
pr_debug("%s\n", __func__);
priv = kmalloc(sizeof(struct vga_arb_private), GFP_KERNEL);
if (priv == NULL)
return -ENOMEM;
memset(priv, 0, sizeof(*priv));
spin_lock_init(&priv->lock);
file->private_data = priv;
spin_lock_irqsave(&vga_user_lock, flags);
list_add(&priv->list, &vga_user_list);
spin_unlock_irqrestore(&vga_user_lock, flags);
/* Set the client' lists of locks */
priv->target = vga_default_device(); /* Maybe this is still null! */
priv->cards[0].pdev = priv->target;
priv->cards[0].io_cnt = 0;
priv->cards[0].mem_cnt = 0;
return 0;
}
static int vga_arb_release(struct inode *inode, struct file *file)
{
struct vga_arb_private *priv = file->private_data;
struct vga_arb_user_card *uc;
unsigned long flags;
int i;
pr_debug("%s\n", __func__);
if (priv == NULL)
return -ENODEV;
spin_lock_irqsave(&vga_user_lock, flags);
list_del(&priv->list);
for (i = 0; i < MAX_USER_CARDS; i++) {
uc = &priv->cards[i];
if (uc->pdev == NULL)
continue;
pr_debug("uc->io_cnt == %d, uc->mem_cnt == %d\n",
uc->io_cnt, uc->mem_cnt);
while (uc->io_cnt--)
vga_put(uc->pdev, VGA_RSRC_LEGACY_IO);
while (uc->mem_cnt--)
vga_put(uc->pdev, VGA_RSRC_LEGACY_MEM);
}
spin_unlock_irqrestore(&vga_user_lock, flags);
kfree(priv);
return 0;
}
static void vga_arb_device_card_gone(struct pci_dev *pdev)
{
}
/*
* callback any registered clients to let them know we have a
* change in VGA cards
*/
static void vga_arbiter_notify_clients(void)
{
struct vga_device *vgadev;
unsigned long flags;
uint32_t new_decodes;
bool new_state;
if (!vga_arbiter_used)
return;
spin_lock_irqsave(&vga_lock, flags);
list_for_each_entry(vgadev, &vga_list, list) {
if (vga_count > 1)
new_state = false;
else
new_state = true;
if (vgadev->set_vga_decode) {
new_decodes = vgadev->set_vga_decode(vgadev->cookie, new_state);
vga_update_device_decodes(vgadev, new_decodes);
}
}
spin_unlock_irqrestore(&vga_lock, flags);
}
static int pci_notify(struct notifier_block *nb, unsigned long action,
void *data)
{
struct device *dev = data;
struct pci_dev *pdev = to_pci_dev(dev);
bool notify = false;
pr_debug("%s\n", __func__);
/* For now we're only intereted in devices added and removed. I didn't
* test this thing here, so someone needs to double check for the
* cases of hotplugable vga cards. */
if (action == BUS_NOTIFY_ADD_DEVICE)
notify = vga_arbiter_add_pci_device(pdev);
else if (action == BUS_NOTIFY_DEL_DEVICE)
notify = vga_arbiter_del_pci_device(pdev);
if (notify)
vga_arbiter_notify_clients();
return 0;
}
static struct notifier_block pci_notifier = {
.notifier_call = pci_notify,
};
static const struct file_operations vga_arb_device_fops = {
.read = vga_arb_read,
.write = vga_arb_write,
.poll = vga_arb_fpoll,
.open = vga_arb_open,
.release = vga_arb_release,
.llseek = noop_llseek,
};
static struct miscdevice vga_arb_device = {
MISC_DYNAMIC_MINOR, "vga_arbiter", &vga_arb_device_fops
};
static int __init vga_arb_device_init(void)
{
int rc;
struct pci_dev *pdev;
rc = misc_register(&vga_arb_device);
if (rc < 0)
pr_err("vgaarb: error %d registering device\n", rc);
bus_register_notifier(&pci_bus_type, &pci_notifier);
/* We add all pci devices satisfying vga class in the arbiter by
* default */
pdev = NULL;
while ((pdev =
pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
PCI_ANY_ID, pdev)) != NULL)
vga_arbiter_add_pci_device(pdev);
pr_info("vgaarb: loaded\n");
return rc;
}
subsys_initcall(vga_arb_device_init);
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