commit 7f62d40d9cb50fd146fe8ff071f98fa3c1855083
author Eric W. Biederman <ebiederm@xmission.com> Wed Feb 09 08:52:41 2022 -0600
committer Eric W. Biederman <ebiederm@xmission.com> Thu Mar 10 13:39:04 2022 -0600
tree fee0257d2a48d176bdfeb84267f3a6d9b1122e0e
parent 8ca07e17c9dd4c4afcb4a3f2ea8f0a0d41c0f982

task_work: Introduce task_work_pending

Wrap the test of task->task_works in a helper function to make
it clear what is being tested.

All of the other readers of task->task_work use READ_ONCE and this is
even necessary on current as other processes can update
task->task_work.  So for consistency I have added READ_ONCE into
task_work_pending.

Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20220309162454.123006-7-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

kernel/signal.c

diff --git a/kernel/signal.c b/kernel/signal.c
index 0e0bd1c..3b4cf25 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2344,7 +2344,7 @@ static void ptrace_do_notify(int signr, int exit_code, int why)
 void ptrace_notify(int exit_code)
 {
 	BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
-	if (unlikely(current->task_works))
+	if (unlikely(task_work_pending(current)))
 		task_work_run();
 
 	spin_lock_irq(&current->sighand->siglock);
@@ -2626,7 +2626,7 @@ bool get_signal(struct ksignal *ksig)
 	struct signal_struct *signal = current->signal;
 	int signr;
 
-	if (unlikely(current->task_works))
+	if (unlikely(task_work_pending(current)))
 		task_work_run();
 
 	/*

kernel/task_work.c

diff --git a/kernel/task_work.c b/kernel/task_work.c
index 1698fbe..cc6fccb 100644
--- a/kernel/task_work.c
+++ b/kernel/task_work.c
@@ -78,7 +78,7 @@ task_work_cancel_match(struct task_struct *task,
 	struct callback_head *work;
 	unsigned long flags;
 
-	if (likely(!task->task_works))
+	if (likely(!task_work_pending(task)))
 		return NULL;
 	/*
 	 * If cmpxchg() fails we continue without updating pprev.