diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2014-09-02 19:57:27 +0200 |
|---|---|---|
| committer | H. Peter Anvin <hpa@linux.intel.com> | 2014-09-02 14:51:16 -0700 |
| commit | 5e23fee23ea10730c752edce1777e6b7e727290f (patch) | |
| tree | 61f1a52fe56b38602b00e8b709f0a456b5ccfaef | |
| parent | f1853505d9ca1c3ea27c29cf83c24661531c527b (diff) | |
| download | tip-5e23fee23ea10730c752edce1777e6b7e727290f.tar.gz | |
x86, fpu: copy_process: Sanitize fpu->last_cpu initialization
Cosmetic, but imho memset(&dst->thread.fpu, 0) is not good simply
because it hides the (important) usage of ->has_fpu/etc from grep.
Change this code to initialize the members explicitly.
And note that ->last_cpu = 0 looks simply wrong, this can confuse
fpu_lazy_restore() if per_cpu(fpu_owner_task, 0) has already exited
and copy_process() re-allocated the same task_struct. Fortunately
this is not actually possible because child->fpu_counter == 0 and
thus fpu_lazy_restore() will not be called, but still this is not
clean/robust.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Link: http://lkml.kernel.org/r/20140902175727.GA21666@redhat.com
Reviewed-by: Suresh Siddha <sbsiddha@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
| -rw-r--r-- | arch/x86/kernel/process.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index b9ba9d52020eb..a44268c897bd7 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -66,7 +66,9 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) { *dst = *src; - memset(&dst->thread.fpu, 0, sizeof(dst->thread.fpu)); + dst->thread.fpu.has_fpu = 0; + dst->thread.fpu.last_cpu = ~0; + dst->thread.fpu.state = NULL; if (tsk_used_math(src)) { int err = fpu_alloc(&dst->thread.fpu); if (err) |