The patch titled
Subject: tile/elf: reorganize notify_exec()
has been added to the -mm tree. Its filename is
tile-elf-reorganize-notify_exec.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/tile-elf-reorganize-notify_exec.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/tile-elf-reorganize-notify_exec.patch
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------------------------------------------------------
From: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Subject: tile/elf: reorganize notify_exec()
This patch series addresses exe_file use for users that require the
mmap_sem for other things (mostly looking up the related vma->vm_file).
In a lot of cases we end up with scenarios where we take the mmap_sem in
get_mm_exe_file(), just to then take it again soon after. This is only
temporary as we will remove the need for mmap_sem when dealing with
exe_file.
This patch (of 3):
In the future mm->exe_file will be done without mmap_sem serialization,
thus isolate and reorganize the tile elf 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.
The visible effects of this patch are:
o We now take and drop the mmap_sem more often. Instead of
just in arch_setup_additional_pages(), we also do it in:
1) get_mm_exe_file()
2) to get the mm->vm_file and notify the simulator.
[Note that 1) will disappear once we change the locking
rules for exe_file.]
o We avoid getting a free page and doing d_path() while
holding the mmap_sem. This requires reordering the checks.
Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx>
Cc: Chris Metcalf <cmetcalf@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/tile/mm/elf.c | 47 ++++++++++++++++++++++++++-----------------
1 file changed, 29 insertions(+), 18 deletions(-)
diff -puN arch/tile/mm/elf.c~tile-elf-reorganize-notify_exec arch/tile/mm/elf.c
--- a/arch/tile/mm/elf.c~tile-elf-reorganize-notify_exec
+++ a/arch/tile/mm/elf.c
@@ -17,6 +17,7 @@
#include <linux/binfmts.h>
#include <linux/compat.h>
#include <linux/mman.h>
+#include <linux/file.h>
#include <linux/elf.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
@@ -39,30 +40,34 @@ static void sim_notify_exec(const char *
static int notify_exec(struct mm_struct *mm)
{
+ int ret = 0;
char *buf, *path;
struct vm_area_struct *vma;
+ struct file *exe_file;
if (!sim_is_simulator())
return 1;
- if (mm->exe_file == NULL)
- return 0;
-
- for (vma = current->mm->mmap; ; vma = vma->vm_next) {
- if (vma == NULL)
- return 0;
- if (vma->vm_file == mm->exe_file)
- break;
- }
-
buf = (char *) __get_free_page(GFP_KERNEL);
if (buf == NULL)
return 0;
- path = d_path(&mm->exe_file->f_path, buf, PAGE_SIZE);
- if (IS_ERR(path)) {
- free_page((unsigned long)buf);
- return 0;
+ exe_file = get_mm_exe_file(mm);
+ if (exe_file == NULL)
+ goto done_free;
+
+ path = d_path(&exe_file->f_path, buf, PAGE_SIZE);
+ if (IS_ERR(path))
+ goto done_put;
+
+ down_read(&mm->mmap_sem);
+ for (vma = current->mm->mmap; ; vma = vma->vm_next) {
+ if (vma == NULL) {
+ up_read(&mm->mmap_sem);
+ goto done_put;
+ }
+ if (vma->vm_file == exe_file)
+ break;
}
/*
@@ -80,14 +85,20 @@ static int notify_exec(struct mm_struct
__insn_mtspr(SPR_SIM_CONTROL,
(SIM_CONTROL_DLOPEN
| (c << _SIM_CONTROL_OPERATOR_BITS)));
- if (c == '\0')
+ if (c == '\0') {
+ ret = 1; /* success */
break;
+ }
}
}
+ up_read(&mm->mmap_sem);
sim_notify_exec(path);
+done_put:
+ fput(exe_file);
+done_free:
free_page((unsigned long)buf);
- return 1;
+ return ret;
}
/* Notify a running simulator, if any, that we loaded an interpreter. */
@@ -109,8 +120,6 @@ int arch_setup_additional_pages(struct l
struct mm_struct *mm = current->mm;
int retval = 0;
- down_write(&mm->mmap_sem);
-
/*
* Notify the simulator that an exec just occurred.
* If we can't find the filename of the mapping, just use
@@ -119,6 +128,8 @@ int arch_setup_additional_pages(struct l
if (!notify_exec(mm))
sim_notify_exec(bprm->filename);
+ down_write(&mm->mmap_sem);
+
retval = setup_vdso_pages();
#ifndef __tilegx__
_
Patches currently in -mm which might be from dave@xxxxxxxxxxxx are
mm-hugetlb-close-race-when-setting-pagetail-for-gigantic-pages.patch
arc-do-not-export-symbols-in-troubleshootc.patch
linux-next.patch
tile-elf-reorganize-notify_exec.patch
oprofile-reduce-mmap_sem-hold-for-mm-exe_file.patch
powerpc-oprofile-reduce-mmap_sem-hold-for-exe_file.patch
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