From 662bbcb2747c2422cf98d3d97619509379eee466 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Sun, 26 May 2013 17:32:23 +0300 Subject: mm, sched: Allow uaccess in atomic with pagefault_disable() This changes might_fault() so that it does not trigger a false positive diagnostic for e.g. the following sequence: spin_lock_irqsave() pagefault_disable() copy_to_user() pagefault_enable() spin_unlock_irqrestore() In particular vhost wants to do this, to call socket ops from under a lock. There are 3 cases to consider: - CONFIG_PROVE_LOCKING - might_fault is non-inline so it's easy to move the in_atomic test to fix up the false positive warning. - CONFIG_DEBUG_ATOMIC_SLEEP - might_fault is currently inline, but we are calling a non-inline __might_sleep anyway, so let's use the non-line version of might_fault that does the right thing. - !CONFIG_DEBUG_ATOMIC_SLEEP && !CONFIG_PROVE_LOCKING __might_sleep is a nop so might_fault is a nop. Make this explicit. Signed-off-by: Michael S. Tsirkin Signed-off-by: Peter Zijlstra Cc: Linus Torvalds Cc: Andrew Morton Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/1369577426-26721-11-git-send-email-mst@redhat.com Signed-off-by: Ingo Molnar --- include/linux/kernel.h | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) (limited to 'include') diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 24719eaa1209..4c7e2e508766 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -193,13 +193,10 @@ extern int _cond_resched(void); (__x < 0) ? -__x : __x; \ }) -#ifdef CONFIG_PROVE_LOCKING +#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP) void might_fault(void); #else -static inline void might_fault(void) -{ - __might_sleep(__FILE__, __LINE__, 0); -} +static inline void might_fault(void) { } #endif extern struct atomic_notifier_head panic_notifier_list; -- cgit v1.2.3