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authorDavidlohr Bueso <dave@stgolabs.net>2015-04-16 12:49:15 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-04-17 09:04:11 -0400
commitfd89a65f155fa890c0130139dfb91684d6da4cfb (patch)
treec0bc5d80caeaa4f7863205acb59c43db66f57da9
parent11163348a23cdbcdca5fb42485418e75f8566a5c (diff)
powerpc/oprofile: reduce mmap_sem hold for exe_file
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>
-rw-r--r--arch/powerpc/oprofile/cell/spu_task_sync.c13
1 files changed, 8 insertions, 5 deletions
diff --git a/arch/powerpc/oprofile/cell/spu_task_sync.c b/arch/powerpc/oprofile/cell/spu_task_sync.c
index 1c27831df1ac..ed7b0977072a 100644
--- a/arch/powerpc/oprofile/cell/spu_task_sync.c
+++ b/arch/powerpc/oprofile/cell/spu_task_sync.c
@@ -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;