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powerpc/oprofile: reduce mmap_sem hold for exe_file

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In the future mm->exe_file will be done without mmap_sem serialization,
thus isolate and reorganize the related code to make the transition
easier.  Good users will, make use of the more standard get_mm_exe_file(),
requiring only holding the mmap_sem to read the value, and relying on
reference counting to make sure that the exe file won't dissappear
underneath us while getting the dcookie.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Robert Richter <rric@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Davidlohr Bueso 2015-04-16 12:49:15 -07:00 committed by Linus Torvalds
parent 11163348a2
commit fd89a65f15
1 changed files with 8 additions and 5 deletions
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13
arch/powerpc/oprofile/cell/spu_task_sync.c
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@ -22,6 +22,7 @@
#include <linux/kref.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/module.h>
#include <linux/notifier.h>
#include <linux/numa.h>
@ -322,18 +323,20 @@ get_exec_dcookie_and_offset(struct spu *spu, unsigned int *offsetp,
unsigned long app_cookie = 0;
unsigned int my_offset = 0;
struct vm_area_struct *vma;
struct file *exe_file;
struct mm_struct *mm = spu->mm;
if (!mm)
goto out;
down_read(&mm->mmap_sem);
if (mm->exe_file) {
app_cookie = fast_get_dcookie(&mm->exe_file->f_path);
pr_debug("got dcookie for %pD\n", mm->exe_file);
exe_file = get_mm_exe_file(mm);
if (exe_file) {
app_cookie = fast_get_dcookie(&exe_file->f_path);
pr_debug("got dcookie for %pD\n", exe_file);
fput(exe_file);
}
down_read(&mm->mmap_sem);
for (vma = mm->mmap; vma; vma = vma->vm_next) {
if (vma->vm_start > spu_ref || vma->vm_end <= spu_ref)
continue;