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| author | Antonino A. Daplas <adaplas@gmail.com> | 2006-08-05 12:14:16 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-08-06 08:57:47 -0700 |
| commit | 78944e549d36673eb6265a2411574e79c28e23dc (patch) | |
| tree | 5e080e775c21f6d7af69f37f37d25b7680cc46b8 /kernel/printk.c | |
| parent | 38cbcdc0a7be69a15462dc49512d43353f34b43b (diff) | |
| download | lwn-78944e549d36673eb6265a2411574e79c28e23dc.tar.gz lwn-78944e549d36673eb6265a2411574e79c28e23dc.zip | |
[PATCH] vt: printk: Fix framebuffer console triggering might_sleep assertion
Reported by: Dave Jones
Whilst printk'ing to both console and serial console, I got this...
(2.6.18rc1)
BUG: sleeping function called from invalid context at kernel/sched.c:4438
in_atomic():0, irqs_disabled():1
Call Trace:
[<ffffffff80271db8>] show_trace+0xaa/0x23d
[<ffffffff80271f60>] dump_stack+0x15/0x17
[<ffffffff8020b9f8>] __might_sleep+0xb2/0xb4
[<ffffffff8029232e>] __cond_resched+0x15/0x55
[<ffffffff80267eb8>] cond_resched+0x3b/0x42
[<ffffffff80268c64>] console_conditional_schedule+0x12/0x14
[<ffffffff80368159>] fbcon_redraw+0xf6/0x160
[<ffffffff80369c58>] fbcon_scroll+0x5d9/0xb52
[<ffffffff803a43c4>] scrup+0x6b/0xd6
[<ffffffff803a4453>] lf+0x24/0x44
[<ffffffff803a7ff8>] vt_console_print+0x166/0x23d
[<ffffffff80295528>] __call_console_drivers+0x65/0x76
[<ffffffff80295597>] _call_console_drivers+0x5e/0x62
[<ffffffff80217e3f>] release_console_sem+0x14b/0x232
[<ffffffff8036acd6>] fb_flashcursor+0x279/0x2a6
[<ffffffff80251e3f>] run_workqueue+0xa8/0xfb
[<ffffffff8024e5e0>] worker_thread+0xef/0x122
[<ffffffff8023660f>] kthread+0x100/0x136
[<ffffffff8026419e>] child_rip+0x8/0x12
This can occur when release_console_sem() is called but the log
buffer still has contents that need to be flushed. The console drivers
are called while the console_may_schedule flag is still true. The
might_sleep() is triggered when fbcon calls console_conditional_schedule().
Fix by setting console_may_schedule to zero earlier, before the call to the
console drivers.
Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel/printk.c')
| -rw-r--r-- | kernel/printk.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/kernel/printk.c b/kernel/printk.c index 65ca0688f86f..1149365e989e 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -799,6 +799,9 @@ void release_console_sem(void) up(&secondary_console_sem); return; } + + console_may_schedule = 0; + for ( ; ; ) { spin_lock_irqsave(&logbuf_lock, flags); wake_klogd |= log_start - log_end; @@ -812,7 +815,6 @@ void release_console_sem(void) local_irq_restore(flags); } console_locked = 0; - console_may_schedule = 0; up(&console_sem); spin_unlock_irqrestore(&logbuf_lock, flags); if (wake_klogd && !oops_in_progress && waitqueue_active(&log_wait)) { |