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From:   "Eric W. Biederman" <ebiederm@xmission.com>
To:     linux-kernel@vger.kernel.org
Cc:     rjw@rjwysocki.net, Oleg Nesterov <oleg@redhat.com>,
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        "Eric W. Biederman" <ebiederm@xmission.com>
Date:   Thu,  5 May 2022 13:26:44 -0500
Message-Id: <20220505182645.497868-11-ebiederm@xmission.com>
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Subject: [PATCH v4 11/12] ptrace: Always take siglock in ptrace_resume
Precedence: bulk

Make code analysis simpler and future changes easier by
always taking siglock in ptrace_resume.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 kernel/ptrace.c | 13 ++-----------
 1 file changed, 2 insertions(+), 11 deletions(-)

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 83ed28262708..36a5b7a00d2f 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -837,8 +837,6 @@ static long ptrace_get_rseq_configuration(struct task_struct *task,
 static int ptrace_resume(struct task_struct *child, long request,
 			 unsigned long data)
 {
-	bool need_siglock;
-
 	if (!valid_signal(data))
 		return -EIO;
 
@@ -874,18 +872,11 @@ static int ptrace_resume(struct task_struct *child, long request,
 	 * Note that we need siglock even if ->exit_code == data and/or this
 	 * status was not reported yet, the new status must not be cleared by
 	 * wait_task_stopped() after resume.
-	 *
-	 * If data == 0 we do not care if wait_task_stopped() reports the old
-	 * status and clears the code too; this can't race with the tracee, it
-	 * takes siglock after resume.
 	 */
-	need_siglock = data && !thread_group_empty(current);
-	if (need_siglock)
-		spin_lock_irq(&child->sighand->siglock);
+	spin_lock_irq(&child->sighand->siglock);
 	child->exit_code = data;
 	wake_up_state(child, __TASK_TRACED);
-	if (need_siglock)
-		spin_unlock_irq(&child->sighand->siglock);
+	spin_unlock_irq(&child->sighand->siglock);
 
 	return 0;
 }
-- 
2.35.3