Linus,
This includes three patches from Oleg Nesterov. The first is a fix to a
race condition that happens between enabling/disabling syscall tracepoints
and new process creations (the check to go into the ptrace path for a process
can be set when it shouldn't, or not set when it should). Not a major bug
but one that should be fixed and even applied to stable.
The other two patches are cleanup/fixes that are not that critical, but
for an -rc1 release would be nice to have. They both deal with syscall
tracepoints.
I would have included these with my initial pull request, but as Oleg
posted his last version as a reply to the bottom of the patch 1/3
thread, I missed it.
Please pull the latest trace-fixes-v3.16-rc1 tree, which can be found at:
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
trace-fixes-v3.16-rc1
Tag SHA1: b6890d3b54aa3ff1aa34afb6c7af367895b9f07a
Head SHA1: 72fa1a896d8ef355e81270667803ceb16a3dd13f
Oleg Nesterov (3):
tracing: Fix syscall_*regfunc() vs copy_process() race
tracing: Change syscall_*regfunc() to check PF_KTHREAD and use
for_each_process_thread()
tracing: syscall_regfunc() should not skip kernel threads
----
include/trace/syscall.h | 15 +++++++++++++++
kernel/fork.c | 2 ++
kernel/tracepoint.c | 26 +++++++++++---------------
3 files changed, 28 insertions(+), 15 deletions(-)
---------------------------
diff --git a/include/trace/syscall.h b/include/trace/syscall.h
index fed853f3d7aa..291c2824fafb 100644
--- a/include/trace/syscall.h
+++ b/include/trace/syscall.h
@@ -4,6 +4,7 @@
#include <linux/tracepoint.h>
#include <linux/unistd.h>
#include <linux/ftrace_event.h>
+#include <linux/thread_info.h>
#include <asm/ptrace.h>
@@ -32,4 +33,18 @@ struct syscall_metadata {
struct ftrace_event_call *exit_event;
};
+#ifdef CONFIG_TRACEPOINTS
+static inline void syscall_tracepoint_update(struct task_struct *p)
+{
+ if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
+ set_tsk_thread_flag(p, TIF_SYSCALL_TRACEPOINT);
+ else
+ clear_tsk_thread_flag(p, TIF_SYSCALL_TRACEPOINT);
+}
+#else
+static inline void syscall_tracepoint_update(struct task_struct *p)
+{
+}
+#endif
+
#endif /* _TRACE_SYSCALL_H */
diff --git a/kernel/fork.c b/kernel/fork.c
index d2799d1fc952..6a13c46cd87d 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1487,7 +1487,9 @@ static struct task_struct *copy_process(unsigned long
clone_flags,
total_forks++;
spin_unlock(¤t->sighand->siglock);
+ syscall_tracepoint_update(p);
write_unlock_irq(&tasklist_lock);
+
proc_fork_connector(p);
cgroup_post_fork(p);
if (clone_flags & CLONE_THREAD)
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 33cbd8c203f8..3490407dc7b7 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -492,33 +492,29 @@ static int sys_tracepoint_refcount;
void syscall_regfunc(void)
{
- unsigned long flags;
- struct task_struct *g, *t;
+ struct task_struct *p, *t;
if (!sys_tracepoint_refcount) {
- read_lock_irqsave(&tasklist_lock, flags);
- do_each_thread(g, t) {
- /* Skip kernel threads. */
- if (t->mm)
- set_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);
- } while_each_thread(g, t);
- read_unlock_irqrestore(&tasklist_lock, flags);
+ read_lock(&tasklist_lock);
+ for_each_process_thread(p, t) {
+ set_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);
+ }
+ read_unlock(&tasklist_lock);
}
sys_tracepoint_refcount++;
}
void syscall_unregfunc(void)
{
- unsigned long flags;
- struct task_struct *g, *t;
+ struct task_struct *p, *t;
sys_tracepoint_refcount--;
if (!sys_tracepoint_refcount) {
- read_lock_irqsave(&tasklist_lock, flags);
- do_each_thread(g, t) {
+ read_lock(&tasklist_lock);
+ for_each_process_thread(p, t) {
clear_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT);
- } while_each_thread(g, t);
- read_unlock_irqrestore(&tasklist_lock, flags);
+ }
+ read_unlock(&tasklist_lock);
}
}
#endif
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