summaryrefslogtreecommitdiff
path: root/include/linux/tracehook.h
diff options
context:
space:
mode:
authorOleg Nesterov <oleg@redhat.com>2012-05-11 04:59:07 +0400
committerAl Viro <viro@zeniv.linux.org.uk>2012-05-24 06:09:21 +0400
commite73f8959af0439d114847eab5a8a5ce48f1217c4 (patch)
tree47f056093590a5e5552e3a75f163e1f798063bda /include/linux/tracehook.h
parent62366c88b29c5a32e1531142092f98eaf49b1103 (diff)
downloadlinux-e73f8959af0439d114847eab5a8a5ce48f1217c4.tar.xz
task_work_add: generic process-context callbacks
Provide a simple mechanism that allows running code in the (nonatomic) context of the arbitrary task. The caller does task_work_add(task, task_work) and this task executes task_work->func() either from do_notify_resume() or from do_exit(). The callback can rely on PF_EXITING to detect the latter case. "struct task_work" can be embedded in another struct, still it has "void *data" to handle the most common/simple case. This allows us to kill the ->replacement_session_keyring hack, and potentially this can have more users. Performance-wise, this adds 2 "unlikely(!hlist_empty())" checks into tracehook_notify_resume() and do_exit(). But at the same time we can remove the "replacement_session_keyring != NULL" checks from arch/*/signal.c and exit_creds(). Note: task_work_add/task_work_run abuses ->pi_lock. This is only because this lock is already used by lookup_pi_state() to synchronize with do_exit() setting PF_EXITING. Fortunately the scope of this lock in task_work.c is really tiny, and the code is unlikely anyway. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: David Howells <dhowells@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Richard Kuo <rkuo@codeaurora.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Alexander Gordeev <agordeev@redhat.com> Cc: Chris Zankel <chris@zankel.net> Cc: David Smith <dsmith@redhat.com> Cc: "Frank Ch. Eigler" <fche@redhat.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'include/linux/tracehook.h')
-rw-r--r--include/linux/tracehook.h11
1 files changed, 11 insertions, 0 deletions
diff --git a/include/linux/tracehook.h b/include/linux/tracehook.h
index b9ca903bb553..b2dd0917ca0d 100644
--- a/include/linux/tracehook.h
+++ b/include/linux/tracehook.h
@@ -49,6 +49,7 @@
#include <linux/sched.h>
#include <linux/ptrace.h>
#include <linux/security.h>
+#include <linux/task_work.h>
struct linux_binprm;
/*
@@ -164,8 +165,10 @@ static inline void tracehook_signal_handler(int sig, siginfo_t *info,
*/
static inline void set_notify_resume(struct task_struct *task)
{
+#ifdef TIF_NOTIFY_RESUME
if (!test_and_set_tsk_thread_flag(task, TIF_NOTIFY_RESUME))
kick_process(task);
+#endif
}
/**
@@ -185,6 +188,14 @@ static inline void tracehook_notify_resume(struct pt_regs *regs)
{
if (current->replacement_session_keyring)
key_replace_session_keyring();
+ /*
+ * The caller just cleared TIF_NOTIFY_RESUME. This barrier
+ * pairs with task_work_add()->set_notify_resume() after
+ * hlist_add_head(task->task_works);
+ */
+ smp_mb__after_clear_bit();
+ if (unlikely(!hlist_empty(&current->task_works)))
+ task_work_run();
}
#endif /* <linux/tracehook.h> */