The patch titled
Subject: usermodehelper: implement UMH_KILLABLE
has been removed from the -mm tree. Its filename was
usermodehelper-implement-umh_killable.patch
This patch was dropped because it was merged into mainline or a subsystem tree
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Subject: usermodehelper: implement UMH_KILLABLE
Implement UMH_KILLABLE, should be used along with UMH_WAIT_EXEC/PROC. The
caller must ensure that subprocess_info->path/etc can not go away until
call_usermodehelper_freeinfo().
call_usermodehelper_exec(UMH_KILLABLE) does wait_for_completion_killable.
If it fails, it uses xchg(&sub_info->complete, NULL) to serialize with
umh_complete() which does the same xhcg() to access sub_info->complete.
If call_usermodehelper_exec wins, it can safely return. umh_complete()
should get NULL and call call_usermodehelper_freeinfo().
Otherwise we know that umh_complete() was already called, in this case
call_usermodehelper_exec() falls back to wait_for_completion() which
should succeed "very soon".
Note: UMH_NO_WAIT == -1 but it obviously should not be used with
UMH_KILLABLE. We delay the neccessary cleanup to simplify the back
porting.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/kmod.h | 2 ++
kernel/kmod.c | 27 +++++++++++++++++++++++++--
2 files changed, 27 insertions(+), 2 deletions(-)
diff -puN include/linux/kmod.h~usermodehelper-implement-umh_killable include/linux/kmod.h
--- a/include/linux/kmod.h~usermodehelper-implement-umh_killable
+++ a/include/linux/kmod.h
@@ -54,6 +54,8 @@ enum umh_wait {
UMH_WAIT_PROC = 1, /* wait for the process to complete */
};
+#define UMH_KILLABLE 4 /* wait for EXEC/PROC killable */
+
struct subprocess_info {
struct work_struct work;
struct completion *complete;
diff -puN kernel/kmod.c~usermodehelper-implement-umh_killable kernel/kmod.c
--- a/kernel/kmod.c~usermodehelper-implement-umh_killable
+++ a/kernel/kmod.c
@@ -201,7 +201,15 @@ EXPORT_SYMBOL(call_usermodehelper_freein
static void umh_complete(struct subprocess_info *sub_info)
{
- complete(sub_info->complete);
+ struct completion *comp = xchg(&sub_info->complete, NULL);
+ /*
+ * See call_usermodehelper_exec(). If xchg() returns NULL
+ * we own sub_info, the UMH_KILLABLE caller has gone away.
+ */
+ if (comp)
+ complete(comp);
+ else
+ call_usermodehelper_freeinfo(sub_info);
}
/* Keventd can't block, but this (a child) can. */
@@ -252,6 +260,9 @@ static void __call_usermodehelper(struct
enum umh_wait wait = sub_info->wait;
pid_t pid;
+ if (wait != UMH_NO_WAIT)
+ wait &= ~UMH_KILLABLE;
+
/* CLONE_VFORK: wait until the usermode helper has execve'd
* successfully We need the data structures to stay around
* until that is done. */
@@ -461,9 +472,21 @@ int call_usermodehelper_exec(struct subp
queue_work(khelper_wq, &sub_info->work);
if (wait == UMH_NO_WAIT) /* task has freed sub_info */
goto unlock;
+
+ if (wait & UMH_KILLABLE) {
+ retval = wait_for_completion_killable(&done);
+ if (!retval)
+ goto wait_done;
+
+ /* umh_complete() will see NULL and free sub_info */
+ if (xchg(&sub_info->complete, NULL))
+ goto unlock;
+ /* fallthrough, umh_complete() was already called */
+ }
+
wait_for_completion(&done);
+wait_done:
retval = sub_info->retval;
-
out:
call_usermodehelper_freeinfo(sub_info);
unlock:
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
origin.patch
linux-next.patch
avr32-dont-mask-signals-in-the-error-path.patch
avr32-use-set_current_blocked-in-handle_signal-sys_rt_sigreturn.patch
avr32-use-block_sigmask.patch
ia64-use-set_current_blocked-and-block_sigmask.patch
microblaze-dont-reimplement-force_sigsegv.patch
microblaze-no-need-to-reset-handler-if-sa_oneshot.patch
microblaze-fix-signal-masking.patch
microblaze-use-set_current_blocked-and-block_sigmask.patch
mips-use-set_current_blocked-and-block_sigmask.patch
score-dont-mask-signals-if-we-fail-to-setup-signal-stack.patch
score-use-set_current_blocked-and-block_sigmask.patch
unicore32-use-block_sigmask.patch
blackfin-use-set_current_blocked-and-block_sigmask.patch
parisc-use-set_current_blocked-and-block_sigmask.patch
mm-coredump-fail-allocations-when-coredumping-instead-of-oom-killing.patch
frv-use-set_current_blocked-and-block_sigmask.patch
sh-no-need-to-reset-handler-if-sa_oneshot.patch
sh-use-set_current_blocked-and-block_sigmask.patch
h8300-use-set_current_blocked-and-block_sigmask.patch
alpha-use-set_current_blocked-and-block_sigmask.patch
m32r-use-set_current_blocked-and-block_sigmask.patch
m68k-use-set_current_blocked-and-block_sigmask.patch
mn10300-use-set_current_blocked-and-block_sigmask.patch
c6x-use-set_current_blocked-and-block_sigmask.patch
cris-use-set_current_blocked-and-block_sigmask.patch
powerpc-eeh-remove-eeh_event_handler-daemonize.patch
pidns-add-reboot_pid_ns-to-handle-the-reboot-syscall.patch
pidns-add-reboot_pid_ns-to-handle-the-reboot-syscall-fix.patch
sysctl-make-kernelns_last_pid-control-being-checkpoint_restore-dependent.patch
fs-proc-introduce-proc-pid-task-tid-children-entry-v9.patch
c-r-prctl-add-ability-to-set-new-mm_struct-exe_file.patch
c-r-prctl-add-ability-to-get-clear_tid_address.patch
c-r-prctl-add-ability-to-get-clear_tid_address-fix.patch
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