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=1794415895; b=J9nIlz06iQcziwjWqReVcjs4u8e4EwTLYQRBGHP+DbcDvZ/ZoaXBkY9Giy6O/wM24KPH JuISqK1uzu7sWsqSPB/0MFGNeAxeSopJ2N0tn46QL8ZTSqe+xbZIy+UVcQc0E3e/Ji0Yk Q0eykTdpoUFUYq7STksGPqwLMt9guCqmIx3h7Lzq53w4SXTM9zrJROBmYbn0VahanOgnJ tpDh02EJxOGl+LKm2RRAoY090OJAUGXqErzx7ieArFAaai4AGQR792sWnSgBcnrp4Y2mS RX0RWJKcloH8Pn9kNzYyGnTkadgnWBszneHz4SbpVd2EtaJidcMmoZdLLp4OHDT1aVQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794415895; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=C9pcx1fHpOz5nBgicIlLlPF1WY/0ltx2cYcEdCmBUsY=; b=fB4Nm4+rpVIEbhbfqg5Qcpfecet81FbZ1biPsX/QIQR0s7cDxjwKiLUUV1Tel7GmRNVi yvcFJf5hAVXKxRqTGhi4ZGrwsN3KrBSx9tTNiflcxKzee2M1AFuITjgs2n2bcNQCHkB11 RdqZH3FOTIW7xwuE7nZ6B0hmzg0kmHypRNNSnpy7ktjuLLoVvrQV/sWZJsIbdVmiOCopJ SaIlNYEjIwPfhQjO7kghLKEslBP0WbV5eGPfeh1AZxcrmkLaqaXj3SeFOV+nLFlHtgzU8 dV5PCYNVnSS5xsDmkNXsO3zWzGZW5jQixmB3CrI3TJjQRFYx1bdaNE/vSL8MJ7+pDJQ== 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=AwaXhrdA; 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 17C2B606A321 for ; Wed, 11 Nov 2026 16:51:35 +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=AwaXhrdA Received: by smtp.kernel.org (Postfix) with ESMTPSA id 714771F00A05; Wed, 11 Nov 2026 16:51:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794415894; bh=C9pcx1fHpOz5nBgicIlLlPF1WY/0ltx2cYcEdCmBUsY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=AwaXhrdAdf6BbrS0a4tgAU27ihXunDKpfMIT6W1bBZVoH4mzEM8PfNqSt1fyLhUdT tFX0winpME9r0K91lPsLF9+9yafncbuPTxz0Up9dgtrQSvE43QKcRP84e8ok3UK/zo sz0KlUEKzoROMKMUb6BkpcSWsFgDA94ynfcAoHqHxRUMINLU9TfgTQbHYpBnQUTAwl 1qaCiJbQlitJ/ZSPJoyKFGh+dWGJZI3uOx+Y4K9wRkuux5bQ+R2Y6+f8kQ3aR131NC 6ReB0Rd2ZzRGtgckcPcvGv2xJKF30QBEhHi2YPRnzJiblyhZVhSW1pQ+Tb6imrfB8d xms68uasDc9wg== From: Sasha Levin To: stable@vger.kernel.org Cc: Hung-Jui Lin , Thomas Gleixner , Sasha Levin Subject: [PATCH 5.15.y] posix-timers: Report zero remaining time for disarmed SIGEV_NONE timers Date: Wed, 11 Nov 2026 11:51:33 -0500 Message-ID: <20261111165103.3363896-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107061201-failed-5.15-141a27750ec3@kernel.org> References: <20261107061201-failed-5.15-141a27750ec3@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 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 fc08d4ccdeeb9..23683372ddcb1 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