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connector/cn_proc: Protect send_msg() with a local lock on RT 

|BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:931
|in_atomic(): 1, irqs_disabled(): 0, pid: 31807, name: sleep
|Preemption disabled at:[<ffffffff8148019b>] proc_exit_connector+0xbb/0x140
|
|CPU: 4 PID: 31807 Comm: sleep Tainted: G        W   E   4.8.0-rt11-rt #106
|Call Trace:
| [<ffffffff813436cd>] dump_stack+0x65/0x88
| [<ffffffff8109c425>] ___might_sleep+0xf5/0x180
| [<ffffffff816406b0>] __rt_spin_lock+0x20/0x50
| [<ffffffff81640978>] rt_read_lock+0x28/0x30
| [<ffffffff8156e209>] netlink_broadcast_filtered+0x49/0x3f0
| [<ffffffff81522621>] ? __kmalloc_reserve.isra.33+0x31/0x90
| [<ffffffff8156e5cd>] netlink_broadcast+0x1d/0x20
| [<ffffffff8147f57a>] cn_netlink_send_mult+0x19a/0x1f0
| [<ffffffff8147f5eb>] cn_netlink_send+0x1b/0x20
| [<ffffffff814801d8>] proc_exit_connector+0xf8/0x140
| [<ffffffff81077f71>] do_exit+0x5d1/0xba0
| [<ffffffff810785cc>] do_group_exit+0x4c/0xc0
| [<ffffffff81078654>] SyS_exit_group+0x14/0x20
| [<ffffffff81640a72>] entry_SYSCALL_64_fastpath+0x1a/0xa4

Since ab8ed95108 ("connector: fix out-of-order cn_proc netlink message
delivery") which is v4.7-rc6.

Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
This commit is contained in:
Mike Galbraith 2016-10-16 05:11:54 +02:00 committed by Alibek Omarov
parent 8ca7ff188f
commit caa6dbd8c9
1 changed files with 4 additions and 2 deletions
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6
drivers/connector/cn_proc.c
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@ -18,6 +18,7 @@
#include <linux/pid_namespace.h>
#include <linux/cn_proc.h>
#include <linux/locallock.h>
/*
* Size of a cn_msg followed by a proc_event structure. Since the
@ -40,10 +41,11 @@ static struct cb_id cn_proc_event_id = { CN_IDX_PROC, CN_VAL_PROC };
/* proc_event_counts is used as the sequence number of the netlink message */
static DEFINE_PER_CPU(__u32, proc_event_counts) = { 0 };
static DEFINE_LOCAL_IRQ_LOCK(send_msg_lock);
static inline void send_msg(struct cn_msg *msg)
{
preempt_disable();
local_lock(send_msg_lock);
msg->seq = __this_cpu_inc_return(proc_event_counts) - 1;
((struct proc_event *)msg->data)->cpu = smp_processor_id();
@ -56,7 +58,7 @@ static inline void send_msg(struct cn_msg *msg)
*/
cn_netlink_send(msg, 0, CN_IDX_PROC, GFP_NOWAIT);
preempt_enable();
local_unlock(send_msg_lock);
}
void proc_fork_connector(struct task_struct *task)