From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E3D753074AC; Mon, 27 Oct 2025 19:10:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761592206; cv=none; b=MzJ6I5M3CUQnhaF1f6W7FHr1bAqU6GiASkeR4X1TzeKJVZTX1Z2ktaC42OQ11GMUznmYmUHLaaecAW83KfMi47lMr1tjiAp3ca9WiKX0UKZwuK08eduXiR3nks9SxPmBc/rH/Ua7X9kCCfg6IcpHR9UwPeHT/YN9bRHC0w376f8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761592206; c=relaxed/simple; bh=O0wCLIIhrKe6gzNvyeZU6Jl5T+5tvl033kbwrhONB/8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=KAkn3uWHNPn5gAbV7vTsefRXx7vl7/PVWiH/libSTetZRPzSqunZ2iXMmHvPFmEqPpuE3tMMQ0iYXD3Bcy0cmS3GV9TL0Lf+E+3Wgwl+xhyWETgd0mU32q4oEgOzyhIwikpvZRE9oDOUDkDg24UXBlwv5izchd6FNi7iKfgxnwk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=bnXkdjiL; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="bnXkdjiL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7624AC4CEF1; Mon, 27 Oct 2025 19:10:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1761592205; bh=O0wCLIIhrKe6gzNvyeZU6Jl5T+5tvl033kbwrhONB/8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bnXkdjiL0qIml7G1objS4OG+zOzoWzr9D5wBYKY5Jb6xFXo/LTck3UuhHP4dQoO3l gLiGyQ77aycjMVsIggFl6O2e6UIHA4HEdEvTG7ewuh6NT4OfmNJEaqAVQflWt9718u O9kcIOzzVN8xLJBnSArW1f/ofRvlTLzpJdy4ioSg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "Steven Rostedt (Google)" , Thomas Gleixner , Guenter Roeck , Jacob Keller , Anna-Maria Behnsen , Jeongjun Park Subject: [PATCH 6.1 033/157] timers: Update the documentation to reflect on the new timer_shutdown() API Date: Mon, 27 Oct 2025 19:34:54 +0100 Message-ID: <20251027183502.181276872@linuxfoundation.org> X-Mailer: git-send-email 2.51.1 In-Reply-To: <20251027183501.227243846@linuxfoundation.org> References: <20251027183501.227243846@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: "Steven Rostedt (Google)" [ Upstream commit a31323bef2b66455920d054b160c17d4240f8fd4 ] In order to make sure that a timer is not re-armed after it is stopped before freeing, a new shutdown state is added to the timer code. The API timer_shutdown_sync() and timer_shutdown() must be called before the object that holds the timer can be freed. Update the documentation to reflect this new workflow. [ tglx: Updated to the new semantics and updated the zh_CN version ] Signed-off-by: Steven Rostedt (Google) Signed-off-by: Thomas Gleixner Tested-by: Guenter Roeck Reviewed-by: Jacob Keller Reviewed-by: Anna-Maria Behnsen Link: https://lore.kernel.org/r/20221110064147.712934793@goodmis.org Link: https://lore.kernel.org/r/20221123201625.375284489@linutronix.de Signed-off-by: Jeongjun Park Signed-off-by: Greg Kroah-Hartman --- Documentation/RCU/Design/Requirements/Requirements.rst | 2 +- Documentation/core-api/local_ops.rst | 2 +- Documentation/kernel-hacking/locking.rst | 5 +++++ Documentation/translations/zh_CN/core-api/local_ops.rst | 2 +- 4 files changed, 8 insertions(+), 3 deletions(-) --- a/Documentation/RCU/Design/Requirements/Requirements.rst +++ b/Documentation/RCU/Design/Requirements/Requirements.rst @@ -1858,7 +1858,7 @@ unloaded. After a given module has been one of its functions results in a segmentation fault. The module-unload functions must therefore cancel any delayed calls to loadable-module functions, for example, any outstanding mod_timer() must be dealt -with via timer_delete_sync() or similar. +with via timer_shutdown_sync() or similar. Unfortunately, there is no way to cancel an RCU callback; once you invoke call_rcu(), the callback function is eventually going to be --- a/Documentation/core-api/local_ops.rst +++ b/Documentation/core-api/local_ops.rst @@ -191,7 +191,7 @@ Here is a sample module which implements static void __exit test_exit(void) { - timer_delete_sync(&test_timer); + timer_shutdown_sync(&test_timer); } module_init(test_init); --- a/Documentation/kernel-hacking/locking.rst +++ b/Documentation/kernel-hacking/locking.rst @@ -1007,6 +1007,11 @@ calling add_timer() at the end of their Because this is a fairly common case which is prone to races, you should use timer_delete_sync() (``include/linux/timer.h``) to +Before freeing a timer, timer_shutdown() or timer_shutdown_sync() should be +called which will keep it from being rearmed. Any subsequent attempt to +rearm the timer will be silently ignored by the core code. + + Locking Speed ============= --- a/Documentation/translations/zh_CN/core-api/local_ops.rst +++ b/Documentation/translations/zh_CN/core-api/local_ops.rst @@ -185,7 +185,7 @@ UP之间没有不同的行为，在你 static void __exit test_exit(void) { - timer_delete_sync(&test_timer); + timer_shutdown_sync(&test_timer); } module_init(test_init);