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Message-ID: <20230606142032.881951490@linutronix.de>
From:   Thomas Gleixner <tglx@linutronix.de>
To:     LKML <linux-kernel@vger.kernel.org>
Cc:     Frederic Weisbecker <frederic@kernel.org>,
        Anna-Maria Behnsen <anna-maria@linutronix.de>,
        John Stultz <jstultz@google.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>,
        Stephen Boyd <sboyd@kernel.org>,
        Eric Biederman <ebiederm@xmission.com>,
        Oleg Nesterov <oleg@redhat.com>
Subject: [patch 33/45] signal: Provide posixtimer_sigqueue_init()
References: <20230606132949.068951363@linutronix.de>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Date:   Tue,  6 Jun 2023 16:38:11 +0200 (CEST)
Precedence: bulk

To cure the SIG_IGN handling for posix interval timers, the preallocated
sigqueue needs to be embedded into struct k_itimer to prevent life time
races of all sorts.

Provide a new function to initialize the embedded sigqueue to prepare for
that.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 include/linux/posix-timers.h |    1 +
 kernel/signal.c              |   11 +++++++++++
 2 files changed, 12 insertions(+)

--- a/include/linux/posix-timers.h
+++ b/include/linux/posix-timers.h
@@ -168,6 +168,7 @@ static inline void posix_cputimers_rt_wa
 }
 
 void posixtimer_rearm_itimer(struct task_struct *p);
+bool posixtimer_init_sigqueue(struct sigqueue *q);
 bool posixtimer_deliver_signal(struct kernel_siginfo *info);
 void posixtimer_free_timer(struct k_itimer *timer);
 
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1901,6 +1901,17 @@ void flush_itimer_signals(void)
 	spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
 }
 
+bool posixtimer_init_sigqueue(struct sigqueue *q)
+{
+	struct ucounts *ucounts = sig_get_ucounts(current, -1, 0);
+
+	if (!ucounts)
+		return false;
+	clear_siginfo(&q->info);
+	__sigqueue_init(q, ucounts, SIGQUEUE_PREALLOC);
+	return true;
+}
+
 struct sigqueue *sigqueue_alloc(void)
 {
 	return __sigqueue_alloc(-1, current, GFP_KERNEL, 0, SIGQUEUE_PREALLOC);