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| author | Nick Piggin <npiggin@suse.de> | 2008-09-10 13:37:17 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-09-10 13:48:49 +0200 |
| commit | c10d38dda1774ed4540380333cabd229eff37094 (patch) | |
| tree | be9649dab7c0017c0a700f146db70f730ad819a7 /arch/x86/lib/usercopy_64.c | |
| parent | 76b189e91845eab3a9d52bb97f971d312d25652d (diff) | |
| download | blackbird-op-linux-c10d38dda1774ed4540380333cabd229eff37094.tar.gz blackbird-op-linux-c10d38dda1774ed4540380333cabd229eff37094.zip | |
x86: some lock annotations for user copy paths
copy_to/from_user and all its variants (except the atomic ones) can take a
page fault and perform non-trivial work like taking mmap_sem and entering
the filesyste/pagecache.
Unfortunately, this often escapes lockdep because a common pattern is to
use it to read in some arguments just set up from userspace, or write data
back to a hot buffer. In those cases, it will be unlikely for page reclaim
to get a window in to cause copy_*_user to fault.
With the new might_lock primitives, add some annotations to x86. I don't
know if I caught all possible faulting points (it's a bit of a maze, and I
didn't really look at 32-bit). But this is a starting point.
Boots and runs OK so far.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/lib/usercopy_64.c')
| -rw-r--r-- | arch/x86/lib/usercopy_64.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c index f4df6e7c718b..847d12945998 100644 --- a/arch/x86/lib/usercopy_64.c +++ b/arch/x86/lib/usercopy_64.c @@ -16,6 +16,8 @@ do { \ long __d0, __d1, __d2; \ might_sleep(); \ + if (current->mm) \ + might_lock_read(¤t->mm->mmap_sem); \ __asm__ __volatile__( \ " testq %1,%1\n" \ " jz 2f\n" \ @@ -65,6 +67,8 @@ unsigned long __clear_user(void __user *addr, unsigned long size) { long __d0; might_sleep(); + if (current->mm) + might_lock_read(¤t->mm->mmap_sem); /* no memory constraint because it doesn't change any memory gcc knows about */ asm volatile( |
