From: Daniel Vetter <daniel.vetter@ffwll.ch> To: LKML <linux-kernel@vger.kernel.org> Cc: DRI Development <dri-devel@lists.freedesktop.org>, linux-fbdev@vger.kernel.org, Alan Cox <alan@lxorguk.ukuu.org.uk>, Daniel Vetter <daniel.vetter@ffwll.ch>, Dave Airlie <airlied@gmail.com>, Thomas Gleixner <tglx@linutronix.de> Subject: [PATCH 1/2] console: use might_sleep in console_lock Date: Wed, 22 Aug 2012 00:34:31 +0200 [thread overview] Message-ID: <1345588472-4055-2-git-send-email-daniel.vetter@ffwll.ch> (raw) In-Reply-To: <1345588472-4055-1-git-send-email-daniel.vetter@ffwll.ch> Instead of BUG_ON(in_interrupt()), since that doesn't check for all the newfangled stuff like preempt. Note that this is valid since the console_sem is essentially used like a real mutex with only two twists: - we allow trylock from hardirq context - across suspend/resume we lock the logical console_lock, but drop the semaphore protecting the locking state. Now that doesn't guarantee that no one is playing tricks in single-thread atomic contexts at suspend/resume/boot time, but - I couldn't find anything suspicious with some grepping, - might_sleep shouldn't die, - and I think the upside of catching more potential issues is worth the risk of getting a might_sleep backtrace that would have been save (and then dealing with that fallout). Cc: Dave Airlie <airlied@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> --- kernel/printk.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/printk.c b/kernel/printk.c index 66a2ea3..ed9af6a 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -1909,7 +1909,8 @@ static int __cpuinit console_cpu_notify(struct notifier_block *self, */ void console_lock(void) { - BUG_ON(in_interrupt()); + might_sleep(); + down(&console_sem); if (console_suspended) return; -- 1.7.10.4
WARNING: multiple messages have this Message-ID (diff)
From: Daniel Vetter <daniel.vetter@ffwll.ch> To: LKML <linux-kernel@vger.kernel.org> Cc: DRI Development <dri-devel@lists.freedesktop.org>, linux-fbdev@vger.kernel.org, Alan Cox <alan@lxorguk.ukuu.org.uk>, Daniel Vetter <daniel.vetter@ffwll.ch>, Dave Airlie <airlied@gmail.com>, Thomas Gleixner <tglx@linutronix.de> Subject: [PATCH 1/2] console: use might_sleep in console_lock Date: Tue, 21 Aug 2012 22:34:31 +0000 [thread overview] Message-ID: <1345588472-4055-2-git-send-email-daniel.vetter@ffwll.ch> (raw) In-Reply-To: <1345588472-4055-1-git-send-email-daniel.vetter@ffwll.ch> Instead of BUG_ON(in_interrupt()), since that doesn't check for all the newfangled stuff like preempt. Note that this is valid since the console_sem is essentially used like a real mutex with only two twists: - we allow trylock from hardirq context - across suspend/resume we lock the logical console_lock, but drop the semaphore protecting the locking state. Now that doesn't guarantee that no one is playing tricks in single-thread atomic contexts at suspend/resume/boot time, but - I couldn't find anything suspicious with some grepping, - might_sleep shouldn't die, - and I think the upside of catching more potential issues is worth the risk of getting a might_sleep backtrace that would have been save (and then dealing with that fallout). Cc: Dave Airlie <airlied@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> --- kernel/printk.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/printk.c b/kernel/printk.c index 66a2ea3..ed9af6a 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -1909,7 +1909,8 @@ static int __cpuinit console_cpu_notify(struct notifier_block *self, */ void console_lock(void) { - BUG_ON(in_interrupt()); + might_sleep(); + down(&console_sem); if (console_suspended) return; -- 1.7.10.4
next prev parent reply other threads:[~2012-08-21 22:35 UTC|newest] Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-08-21 22:34 [PATCH 0/2] console_lock debug improvements Daniel Vetter 2012-08-21 22:34 ` Daniel Vetter 2012-08-21 22:34 ` Daniel Vetter 2012-08-21 22:34 ` Daniel Vetter [this message] 2012-08-21 22:34 ` [PATCH 1/2] console: use might_sleep in console_lock Daniel Vetter 2012-08-21 22:34 ` [PATCH 2/2] console: implement lockdep support for console_lock Daniel Vetter 2012-08-21 22:34 ` Daniel Vetter 2012-08-22 13:18 ` [PATCH 0/2] console_lock debug improvements Alan Cox 2012-08-22 13:18 ` Alan Cox
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