From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794416281; b=aOUrdO7Gu1ARJL6jB0cFFfaGNVAFFSy2lleaeZy8PaOPMVqj2YW5qreXaA4mtNNJGCiC +Wyb5jIKPsmxt12CCzYEgyF3BiEyxsK7iDnR0iExEg/v9RsAYmIooj2hKzcfD77QKqoVF TxFwKwYCBdr1ni8SciZzmUdP3ZPQnjNcOBwGp+YzEnReEno1hO6HYpuoSFYL2eyHky5T6 Xxcfr1XjUf0XhfkS0yipwiLkMPkudYxd5AzAoqw0afi0IzOJGhFlXRhEEWVC7cxjgbnCm 0idqTzIweiCo9pB/o1jVBfAjoxV2gffu08X68j68sO0OTsn1b8FyRkCsJW2aVGUnwgw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794416281; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=aLMI+bwke2/rRwGLJ0LNs2GaDspb0ENLvzSkAdUbmm4=; b=DKzCgMwWRjKlRQzKe20XXFIvuoiO6KHPt/MFuaixT6YnFyPeyu/OrQVx0ZrqtNQKAmIW 1NHw9ZTrVg4SLDitkTuXBCscs9u1E/fX/kV0epFCGCpP0MK29qV8aT5dm5TVtGUA5ueQB vKkdT/th/nn+DIapYCz9Ub8clsC9zyXnnZK3aNEALLDXPkixABL7sD2sF1y6NLNp0EoSB 3KH0hwRwyZ07XkFYU73I73mhEWfuiOyMW78xMG4/BY8ZFDHzVbHowY9T+Z5cUTqUSODYT sltvmei1bxIPbl2RV9yglm13+99hcTwE93hBUQ4pkk4BF6+haO/3FqDVicpFmKnazHw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=MboI9S7j; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 61E9B606A330 for ; Wed, 11 Nov 2026 16:58:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=MboI9S7j Received: by smtp.kernel.org (Postfix) with ESMTPSA id 670531F00A06; Wed, 11 Nov 2026 16:58:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794416280; bh=aLMI+bwke2/rRwGLJ0LNs2GaDspb0ENLvzSkAdUbmm4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=MboI9S7jfRekkuG0jdfVRwT1CZKbuHixBUzjffmvMD/QkA6JKBcVHso9CrHFKZnea pLu9QXWjn4CMHmPqMSjDjHj8t0TY/6TC3RY+NTTG5KpNkIQnD+b36JXPTIPTS4VUdA AClE7FbKIsk+/bqGNFBAGaq7ei52PbhLsIEYs0wzp6O45k7GqzqXbSX+iGR5QMfMvn NH7BangEl+shiYbmwzm6MEGKpOuZgmm7CczP0WqCAIimYth5D0vN7jSf2SQZauZF+9 4I6aGj0QrjJtH2J6Hs2aVdI7BJcRxoLtSLptVVBDBu6DycQF53mfZl3BsIZmCJlSBU ojwllxETqzN0w== From: Sasha Levin To: stable@vger.kernel.org Cc: Hung-Jui Lin , Thomas Gleixner , Sasha Levin Subject: [PATCH 5.10.y] posix-timers: Report zero remaining time for disarmed SIGEV_NONE timers Date: Wed, 11 Nov 2026 11:57:59 -0500 Message-ID: <20261111165732.3393965-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107062900-failed-5.10-141a27750ec3@kernel.org> References: <20261107062900-failed-5.10-141a27750ec3@kernel.org> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Hung-Jui Lin [ Upstream commit 141a27750ec3d91ad9d1ad1764ebb5e51b963478 ] SIGEV_NONE timers are never queued. common_timer_get() emulates their expiry by computing the remaining time from the stored expiry value. Because an armed SIGEV_NONE oneshot timer is not queued, its it_status stays POSIX_TIMER_DISARMED. So common_timer_get() cannot use it_status to skip a disarmed SIGEV_NONE timer and evaluates the stored expiry value for all SIGEV_NONE timers. Disarming a timer with timer_settime() and a zero it_value cancels the timer and sets it_status to POSIX_TIMER_DISARMED, but leaves the expiry value unchanged. As a consequence, timer_gettime() on a disarmed SIGEV_NONE timer reports the remaining time of the previous arming until that time has passed, instead of zero as POSIX requires for a disarmed timer. Example with a CLOCK_MONOTONIC timer armed with it_value = 10ms and it_interval = 100ms, then disarmed with an all-zero itimerspec: armed: it_value = 0.009999000 it_interval = 0.100000000 disarmed: it_value = 0.008700792 it_interval = 0.000000000 SIGEV_SIGNAL timers and SIGEV_NONE CPU timers report zero in the same situation. All clocks which use common_timer_get() are affected, including the alarm timer clocks. Mark SIGEV_NONE timers as POSIX_TIMER_ARMED when they are armed, so that common_timer_get() returns early for every disarmed timer. Forward SIGEV_NONE interval timers in common_timer_get() regardless of it_status, as they are never queued and therefore never forwarded by the expiry code. After the change the disarmed timer above reports zero. Armed SIGEV_NONE oneshot and interval timers on CLOCK_MONOTONIC, CLOCK_REALTIME, CLOCK_BOOTTIME and CLOCK_BOOTTIME_ALARM still report their remaining time, and the posix_timers selftest passes. Fixes: becf8b5d00f4 ("[PATCH] hrtimer: convert posix timers completely") Signed-off-by: Hung-Jui Lin Signed-off-by: Thomas Gleixner Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20261023151411.28685-1-alex.lin.programmer@gmail.com [ sashal: adapted it_status state handling to the it_active boolean flag ] Signed-off-by: Sasha Levin --- kernel/time/posix-timers.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c index 3a68c650ff2a3..2f1cefa2499a8 100644 --- a/kernel/time/posix-timers.c +++ b/kernel/time/posix-timers.c @@ -686,12 +686,8 @@ void common_timer_get(struct k_itimer *timr, struct itimerspec64 *cur_setting) if (iv) { cur_setting->it_interval = ktime_to_timespec64(iv); } else if (!timr->it_active) { - /* - * SIGEV_NONE oneshot timers are never queued. Check them - * below. - */ - if (!sig_none) - return; + /* Nothing to update for a disarmed timer */ + return; } now = kc->clock_get_ktime(timr->it_clock); @@ -901,7 +897,15 @@ int common_timer_set(struct k_itimer *timr, int flags, sigev_none = timr->it_sigev_notify == SIGEV_NONE; kc->timer_arm(timr, expires, flags & TIMER_ABSTIME, sigev_none); - timr->it_active = !sigev_none; + /* + * SIGEV_NONE timers are not queued, but mark them armed + * so that common_timer_get() can tell them apart from + * disarmed timers. An expired SIGEV_NONE timer stays + * armed, which is harmless: common_timer_get() reports + * zero remaining time for it and it never reaches the + * signal delivery code. + */ + timr->it_active = 1; return 0; } -- 2.53.0