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Filename Latest commit message Latest commit date
Kees Cook 52f737c2da timer: Provide wrappers safe for use with LOCKDEP
Under LOCKDEP, the timer lock_class_key (set up in __setup_timer) needs
to be tied to the caller's context, so an inline for timer_setup()
won't work. We do, however, want to keep the inline version around for
argument type checking, though, so this provides macro wrappers in the
LOCKDEP case.

This fixes the case of different timers sharing the same LOCKDEP instance,
and producing a false positive warning:

[  580.840858] ======================================================
[  580.842299] WARNING: possible circular locking dependency detected
[  580.843684] 4.14.0-rc4+ #17 Not tainted
[  580.844554] ------------------------------------------------------
[  580.845945] swapper/9/0 is trying to acquire lock:
[  580.847024]  (slock-AF_INET){+.-.}, at: [<ffffffff84ea4c34>] tcp_write_timer+0x24/0xd0
[  580.848834]
               but task is already holding lock:
[  580.850107]  ((timer)#2){+.-.}, at: [<ffffffff846df7c0>] call_timer_fn+0x0/0x300
[  580.851663]
               which lock already depends on the new lock.

[  580.853439]
               the existing dependency chain (in reverse order) is:
[  580.855311]
               -> #1 ((timer)#2){+.-.}:
[  580.856538]        __lock_acquire+0x114d/0x11a0
[  580.857506]        lock_acquire+0xb0/0x1d0
[  580.858373]        del_timer_sync+0x3c/0xb0
[  580.859260]        inet_csk_reqsk_queue_drop+0x7f/0x1b0
...
               -> #0 (slock-AF_INET){+.-.}:
[  580.884980]        check_prev_add+0x666/0x700
[  580.885790]        __lock_acquire+0x114d/0x11a0
[  580.886575]        lock_acquire+0xb0/0x1d0
[  580.887289]        _raw_spin_lock+0x2c/0x40
[  580.888021]        tcp_write_timer+0x24/0xd0
...
[  580.900055]  Possible unsafe locking scenario:

[  580.901043]        CPU0                    CPU1
[  580.901797]        ----                    ----
[  580.902540]   lock((timer)#2);
[  580.903046]                                lock(slock-AF_INET);
[  580.904006]                                lock((timer)#2);
[  580.904915]   lock(slock-AF_INET);
[  580.905502]

In this report, del_timer_sync() is from:

	inet_csk_reqsk_queue_drop()
		reqsk_queue_unlink()
			del_timer_sync(&req->rsk_timer)

but tcp_write_timer()'s timer is attached to icsk_retransmit_timer. Both
had the same lock_class_key, since they were using timer_setup(). Switching
to a macro allows for a separate context, avoiding the false positive.

Fixes: 686fef928b ("timer: Prepare to change timer callback argument type")
Reported-by: Craig Gallek <cgallek@google.com>
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: netdev@vger.kernel.org
Cc: "David S. Miller" <davem@davemloft.net>
Link: https://lkml.kernel.org/r/20171019202838.GA43223@beast
2017-10-20 11:07:46 +02:00
arch timer: Remove expires and data arguments from DEFINE_TIMER 2017-10-05 15:01:20 +02:00
block block: fix a crash caused by wrong API 2017-09-25 08:56:05 -06:00
certs
crypto crypto: af_alg - update correct dst SGL entry 2017-09-20 17:42:42 +08:00
Documentation Merge branch 'for-4.14-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq 2017-10-03 10:44:03 -07:00
drivers ahci: Convert timers to use timer_setup() 2017-10-19 23:15:16 +02:00
firmware
fs timer: Remove expires and data arguments from DEFINE_TIMER 2017-10-05 15:01:20 +02:00
include timer: Provide wrappers safe for use with LOCKDEP 2017-10-20 11:07:46 +02:00
init
ipc fix a typo in put_compat_shm_info() 2017-09-25 20:41:46 -04:00
kernel clockevents: Retry programming min delta up to 10 times 2017-10-19 16:29:15 +02:00
lib timer: Remove expires and data arguments from DEFINE_TIMER 2017-10-05 15:01:20 +02:00
mm percpu: fix iteration to prevent skipping over block 2017-09-28 07:39:27 -07:00
net timer: Remove expires and data arguments from DEFINE_TIMER 2017-10-05 15:01:20 +02:00
samples
scripts objtool: Skip unreachable warnings for GCC 4.4 and older 2017-09-28 07:23:02 +02:00
security timer: Remove expires and data arguments from DEFINE_TIMER 2017-10-05 15:01:20 +02:00
sound timer: Remove expires and data arguments from DEFINE_TIMER 2017-10-05 15:01:20 +02:00
tools Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-10-01 12:06:31 -07:00
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MAINTAINERS LED fixes for 4.14-rc3 2017-09-29 19:33:32 -07:00
Makefile Linux 4.14-rc3 2017-10-01 14:54:54 -07:00
README

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.