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authorMichael S. Tsirkin <mst@redhat.com>2013-05-26 17:32:23 +0300
committerIngo Molnar <mingo@kernel.org>2013-05-28 09:41:11 +0200
commit662bbcb2747c2422cf98d3d97619509379eee466 (patch)
treed733c7257e59bde654d963cce0e26454a134d787 /include/linux/kernel.h
parent114276ac0a3beb9c391a410349bd770653e185ce (diff)
downloadop-kernel-dev-662bbcb2747c2422cf98d3d97619509379eee466.zip
op-kernel-dev-662bbcb2747c2422cf98d3d97619509379eee466.tar.gz
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 <mst@redhat.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1369577426-26721-11-git-send-email-mst@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux/kernel.h')
-rw-r--r--include/linux/kernel.h7
1 files changed, 2 insertions, 5 deletions
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 24719ea..4c7e2e5 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;
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