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perf: Kill the dead !vma->vm_mm code in perf_event_mmap_event() 

1. perf_event_mmap(vma) is never called with a gate_vma-like arg,
   remove the "if (!vma->vm_mm)" code.

2. arch_vma_name() can use the chached value of mmap_event->vma.

3. Change the code to not call arch_vma_name() twice.

4. Purely cosmetic, but since we use "goto got_name" all the time
   remove "else" from "[stack]" branch just for symmetry.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20131016200945.GB23214@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Oleg Nesterov 2013-10-16 22:09:45 +02:00 committed by Ingo Molnar
parent d9494cb429
commit 32c5fb7e7d
1 changed files with 6 additions and 8 deletions
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14
kernel/events/core.c
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@ -5136,21 +5136,19 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event)
min = MINOR(dev);
} else {
if (arch_vma_name(mmap_event->vma)) {
name = strncpy(tmp, arch_vma_name(mmap_event->vma),
sizeof(tmp) - 1);
name = arch_vma_name(vma);
if (name) {
name = strncpy(tmp, name, sizeof(tmp) - 1);
tmp[sizeof(tmp) - 1] = '\0';
goto got_name;
}
if (!vma->vm_mm) {
name = strncpy(tmp, "[vdso]", sizeof(tmp));
goto got_name;
} else if (vma->vm_start <= vma->vm_mm->start_brk &&
if (vma->vm_start <= vma->vm_mm->start_brk &&
vma->vm_end >= vma->vm_mm->brk) {
name = strncpy(tmp, "[heap]", sizeof(tmp));
goto got_name;
} else if (vma->vm_start <= vma->vm_mm->start_stack &&
}
if (vma->vm_start <= vma->vm_mm->start_stack &&
vma->vm_end >= vma->vm_mm->start_stack) {
name = strncpy(tmp, "[stack]", sizeof(tmp));
goto got_name;