Commit-ID: 5e23fee23ea10730c752edce1777e6b7e727290f Gitweb: http://git.kernel.org/tip/5e23fee23ea10730c752edce1777e6b7e727290f Author: Oleg Nesterov <o...@redhat.com> AuthorDate: Tue, 2 Sep 2014 19:57:27 +0200 Committer: H. Peter Anvin <h...@linux.intel.com> CommitDate: Tue, 2 Sep 2014 14:51:16 -0700
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 <o...@redhat.com> Link: http://lkml.kernel.org/r/20140902175727.ga21...@redhat.com Reviewed-by: Suresh Siddha <sbsid...@gmail.com> Signed-off-by: H. Peter Anvin <h...@linux.intel.com> --- arch/x86/kernel/process.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index b9ba9d5..a44268c 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) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
