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| author | Brian Gerst <brgerst@gmail.com> | 2010-09-04 03:17:12 +0200 |
|---|---|---|
| committer | H. Peter Anvin <hpa@linux.intel.com> | 2010-09-09 23:16:45 +0200 |
| commit | a4d4fbc7735bba6654b20f859135f9d3f8fe7f76 (patch) | |
| tree | 4b501fbfbce08e3222f137a284b354425162f873 /arch/x86/kernel | |
| parent | x86, fpu: Merge __save_init_fpu() (diff) | |
| download | linux-a4d4fbc7735bba6654b20f859135f9d3f8fe7f76.tar.xz linux-a4d4fbc7735bba6654b20f859135f9d3f8fe7f76.zip | |
x86-64, fpu: Disable preemption when using TS_USEDFPU
Consolidates code and fixes the below race for 64-bit.
commit 9fa2f37bfeb798728241cc4a19578ce6e4258f25
Author: torvalds <torvalds>
Date: Tue Sep 2 07:37:25 2003 +0000
Be a lot more careful about TS_USEDFPU and preemption
We had some races where we testecd (or set) TS_USEDFPU together
with sequences that depended on the setting (like clearing or
setting the TS flag in %cr0) and we could be preempted in between,
which screws up the FPU state, since preemption will itself change
USEDFPU and the TS flag.
This makes it a lot more explicit: the "internal" low-level FPU
functions ("__xxxx_fpu()") all require preemption to be disabled,
and the exported "real" functions will make sure that is the case.
One case - in __switch_to() - was switched to the non-preempt-safe
internal version, since the scheduler itself has already disabled
preemption.
BKrev: 3f5448b5WRiQuyzAlbajs3qoQjSobw
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
LKML-Reference: <1283563039-3466-6-git-send-email-brgerst@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/kernel')
| -rw-r--r-- | arch/x86/kernel/process_64.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 3d9ea531ddd1..b3d7a3a04f38 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -424,7 +424,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) load_TLS(next, cpu); /* Must be after DS reload */ - unlazy_fpu(prev_p); + __unlazy_fpu(prev_p); /* Make sure cpu is ready for new context */ if (preload_fpu) |