[PATCH 3/3] powerpc/oprofile: reduce mmap_sem hold for exe_file
From: Davidlohr Bueso <dave@stgolabs.net>
Date: 2015-02-25 21:59:16
Also in:
linuxppc-dev, lkml
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
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. Cc: Arnd Bergmann <arnd@arndb.de> Cc: Robert Richter <rric@kernel.org> Cc: linuxppc-dev@lists.ozlabs.org Cc: cbe-oss-dev@lists.ozlabs.org Cc: oprofile-list@lists.sourceforge.net Signed-off-by: Davidlohr Bueso <redacted> --- Completely untested. arch/powerpc/oprofile/cell/spu_task_sync.c | 13 ++++++++----- 1 file 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 1c27831..ed7b097 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;
--
2.1.4
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>