The patch titled Subject: usermodehelper: implement UMH_KILLABLE has been added to the -mm tree. Its filename is usermodehelper-implement-umh_killable.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ 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: _ Subject: Subject: usermodehelper: implement UMH_KILLABLE Patches currently in -mm which might be from oleg@xxxxxxxxxx are linux-next.patch arm-use-set_current_blocked-and-block_sigmask.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 powerpc-use-set_current_blocked-and-block_sigmask.patch hexagon-use-set_current_blocked-and-block_sigmask.patch tile-use-set_current_blocked-and-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 openrisc-dont-reimplement-force_sigsegv.patch openrisc-no-need-to-reset-handler-if-sa_oneshot.patch openrisc-dont-mask-signals-if-we-fail-to-setup-signal-stack.patch openrisc-use-set_current_blocked-and-block_sigmask.patch parisc-use-set_current_blocked-and-block_sigmask.patch s390-use-block_sigmask.patch xtensa-dont-reimplement-force_sigsegv.patch xtensa-no-need-to-reset-handler-if-sa_oneshot.patch xtensa-dont-mask-signals-if-we-fail-to-setup-signal-stack.patch xtensa-use-set_current_blocked-and-block_sigmask.patch sparc-use-block_sigmask.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 um-dont-restore-current-blocked-on-error.patch um-use-set_current_blocked-and-block_sigmask.patch prctl-add-pr_setget_child_subreaper-to-allow-simple-process-supervision.patch prctl-add-pr_setget_child_subreaper-to-allow-simple-process-supervision-fix.patch prctl-add-pr_setget_child_subreaper-to-allow-simple-process-supervision-fix-fix.patch kernel-exitc-if-init-dies-log-a-signal-which-killed-it-if-any.patch kernel-exitc-if-init-dies-log-a-signal-which-killed-it-if-any-fix.patch signal-give-send_sig_forced-more-power-to-beat-signal_unkillable.patch signal-cosmetic-s-from_ancestor_ns-force-in-prepare_signal-paths.patch signal-oom_kill_task-use-send_sig_forced-instead-of-force_sig.patch signal-zap_pid_ns_processes-s-send_sig_noinfo-send_sig_forced.patch usermodehelper-use-umh_wait_proc-consistently.patch usermodehelper-introduce-umh_completesub_info.patch usermodehelper-implement-umh_killable.patch usermodehelper-kill-umh_wait-renumber-umh_-constants.patch usermodehelper-____call_usermodehelper-doesnt-need-do_exit.patch kmod-introduce-call_modprobe-helper.patch kmod-make-__request_module-killable.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 -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html