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authorOleg Nesterov <oleg@redhat.com>2010-05-26 14:43:08 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-05-27 09:12:45 -0700
commit269b005a28e124a341df4adef2c3661cf7371fcc (patch)
tree226b105cc4c1bbe0b3fe92f2733708a7dc2dedb8 /fs/exec.c
parent5e43aef530ba39206f7923295388f7ec3c5a7d93 (diff)
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coredump: shift down_write(mmap_sem) into coredump_wait()
- move the cprm.mm_flags checks up, before we take mmap_sem - move down_write(mmap_sem) and ->core_state check from do_coredump() to coredump_wait() This simplifies the code and makes the locking symmetrical. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: David Howells <dhowells@redhat.com> Cc: Neil Horman <nhorman@tuxdriver.com> Cc: Roland McGrath <roland@redhat.com> Cc: Andi Kleen <andi@firstfloor.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/exec.c')
-rw-r--r--fs/exec.c19
1 files changed, 7 insertions, 12 deletions
diff --git a/fs/exec.c b/fs/exec.c
index 6501823b7a1..0c72d23ed0e 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1662,12 +1662,15 @@ static int coredump_wait(int exit_code, struct core_state *core_state)
struct task_struct *tsk = current;
struct mm_struct *mm = tsk->mm;
struct completion *vfork_done;
- int core_waiters;
+ int core_waiters = -EBUSY;
init_completion(&core_state->startup);
core_state->dumper.task = tsk;
core_state->dumper.next = NULL;
- core_waiters = zap_threads(tsk, mm, core_state, exit_code);
+
+ down_write(&mm->mmap_sem);
+ if (!mm->core_state)
+ core_waiters = zap_threads(tsk, mm, core_state, exit_code);
up_write(&mm->mmap_sem);
if (unlikely(core_waiters < 0))
@@ -1860,20 +1863,12 @@ void do_coredump(long signr, int exit_code, struct pt_regs *regs)
binfmt = mm->binfmt;
if (!binfmt || !binfmt->core_dump)
goto fail;
+ if (!__get_dumpable(cprm.mm_flags))
+ goto fail;
cred = prepare_creds();
if (!cred)
goto fail;
-
- down_write(&mm->mmap_sem);
- /*
- * If another thread got here first, or we are not dumpable, bail out.
- */
- if (mm->core_state || !__get_dumpable(cprm.mm_flags)) {
- up_write(&mm->mmap_sem);
- goto fail_creds;
- }
-
/*
* We cannot trust fsuid as being the "true" uid of the
* process nor do we know its entire history. We only know it