linux/drivers/tty
Arnd Bergmann 287980e49f remove lots of IS_ERR_VALUE abuses
Most users of IS_ERR_VALUE() in the kernel are wrong, as they
pass an 'int' into a function that takes an 'unsigned long'
argument. This happens to work because the type is sign-extended
on 64-bit architectures before it gets converted into an
unsigned type.

However, anything that passes an 'unsigned short' or 'unsigned int'
argument into IS_ERR_VALUE() is guaranteed to be broken, as are
8-bit integers and types that are wider than 'unsigned long'.

Andrzej Hajda has already fixed a lot of the worst abusers that
were causing actual bugs, but it would be nice to prevent any
users that are not passing 'unsigned long' arguments.

This patch changes all users of IS_ERR_VALUE() that I could find
on 32-bit ARM randconfig builds and x86 allmodconfig. For the
moment, this doesn't change the definition of IS_ERR_VALUE()
because there are probably still architecture specific users
elsewhere.

Almost all the warnings I got are for files that are better off
using 'if (err)' or 'if (err < 0)'.
The only legitimate user I could find that we get a warning for
is the (32-bit only) freescale fman driver, so I did not remove
the IS_ERR_VALUE() there but changed the type to 'unsigned long'.
For 9pfs, I just worked around one user whose calling conventions
are so obscure that I did not dare change the behavior.

I was using this definition for testing:

 #define IS_ERR_VALUE(x) ((unsigned long*)NULL == (typeof (x)*)NULL && \
       unlikely((unsigned long long)(x) >= (unsigned long long)(typeof(x))-MAX_ERRNO))

which ends up making all 16-bit or wider types work correctly with
the most plausible interpretation of what IS_ERR_VALUE() was supposed
to return according to its users, but also causes a compile-time
warning for any users that do not pass an 'unsigned long' argument.

I suggested this approach earlier this year, but back then we ended
up deciding to just fix the users that are obviously broken. After
the initial warning that caused me to get involved in the discussion
(fs/gfs2/dir.c) showed up again in the mainline kernel, Linus
asked me to send the whole thing again.

[ Updated the 9p parts as per Al Viro  - Linus ]

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Andrzej Hajda <a.hajda@samsung.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lkml.org/lkml/2016/1/7/363
Link: https://lkml.org/lkml/2016/5/27/486
Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> # For nvmem part
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-27 15:26:11 -07:00
..
hvc tty: hvc_console: silence unintialized variable warning 2016-04-30 09:26:55 -07:00
ipwireless tty: ipwireless: fix possible NULL dereference 2016-04-30 09:26:55 -07:00
serial remove lots of IS_ERR_VALUE abuses 2016-05-27 15:26:11 -07:00
vt tty: vt, finish looping on duplicate 2016-05-03 15:59:15 -07:00
Kconfig tty: cyclades: cyz_interrupt is only used for PCI 2016-02-06 23:41:17 -08:00
Makefile TTY: Add MIPS EJTAG Fast Debug Channel TTY driver 2015-03-31 12:04:12 +02:00
amiserial.c tty: Replace ASYNC_INITIALIZED bit and update atomically 2016-04-30 09:26:55 -07:00
bfin_jtag_comm.c TTY: bfin_jtag_comm: remove incorrect wait_until_sent operation 2015-03-07 03:44:14 +01:00
cyclades.c tty: Replace ASYNC_INITIALIZED bit and update atomically 2016-04-30 09:26:55 -07:00
ehv_bytechan.c drivers/tty: make ehv_bytechan.c explicitly non-modular 2016-02-06 23:26:43 -08:00
goldfish.c tty: goldfish: support platform_device with id -1 2016-03-07 16:11:14 -08:00
isicom.c tty: Replace ASYNC_INITIALIZED bit and update atomically 2016-04-30 09:26:55 -07:00
metag_da.c tty/metag_da: Avoid module_init/module_exit in non-modular code 2015-06-16 14:12:31 -04:00
mips_ejtag_fdc.c ttyFDC: Fix build problems due to use of module_{init,exit} 2015-10-17 21:29:21 -07:00
moxa.c tty: Replace ASYNC_INITIALIZED bit and update atomically 2016-04-30 09:26:55 -07:00
moxa.h
mxser.c tty: mxser: Remove unused ASYNC_SHARE_IRQ flag 2016-04-30 09:26:55 -07:00
mxser.h
n_gsm.c TTY and Serial driver update for 4.7-rc1 2016-05-20 20:57:27 -07:00
n_hdlc.c Fix OpenSSH pty regression on close 2016-05-01 13:22:54 -07:00
n_r3964.c tty: r3964: Replace/remove bogus tty lock use 2015-10-17 21:11:29 -07:00
n_tracerouter.c n_tracerouter: stop including <asm-generic/bug> 2015-10-15 00:21:10 +02:00
n_tracesink.c n_tracesink: stop including <asm-generic/bug> 2015-10-15 00:21:11 +02:00
n_tracesink.h
n_tty.c Fix OpenSSH pty regression on close 2016-05-01 13:22:54 -07:00
nozomi.c tty: Replace TTY_THROTTLED bit tests with tty_throttled() 2016-04-30 09:26:55 -07:00
pty.c Merge 4.6-rc7 into tty-next 2016-05-09 09:39:13 +02:00
rocket.c TTY: add __init attribute 2016-04-30 09:26:55 -07:00
rocket.h tty: rocket: fix comment of ROCKET_SPD_HI 2015-05-24 12:49:16 -07:00
rocket_int.h tty: rocket: Remove private close_wait 2016-01-28 14:13:44 -08:00
synclink.c TTY and Serial driver update for 4.7-rc1 2016-05-20 20:57:27 -07:00
synclink_gt.c TTY and Serial driver update for 4.7-rc1 2016-05-20 20:57:27 -07:00
synclinkmp.c TTY and Serial driver update for 4.7-rc1 2016-05-20 20:57:27 -07:00
sysrq.c sysrq: Fix warning in sysrq generated crash. 2015-12-29 16:29:18 -08:00
tty_audit.c tty: audit: remove unused variable 2016-03-07 16:11:14 -08:00
tty_buffer.c Fix OpenSSH pty regression on close 2016-05-01 13:22:54 -07:00
tty_io.c Merge 4.6-rc7 into tty-next 2016-05-09 09:39:13 +02:00
tty_ioctl.c tty: Replace TTY_THROTTLED bit tests with tty_throttled() 2016-04-30 09:26:55 -07:00
tty_ldisc.c tty: Eliminate global symbol tty_ldisc_N_TTY 2016-01-27 15:13:28 -08:00
tty_ldsem.c tty: Deinline __ldsem_down_write_nested, save 128 bytes 2015-12-13 19:59:48 -08:00
tty_mutex.c Merge 4.5-rc4 into tty-next 2016-02-14 14:36:04 -08:00
tty_port.c tty: Replace ASYNC_INITIALIZED bit and update atomically 2016-04-30 09:26:55 -07:00