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 73BF615FA85; Wed, 10 Apr 2024 14:00:20 +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=1712757620; cv=none; b=PIuuD+Qqocq08IUs5qmXCOEMub9pFqptgogoMQnxsPAWEfuHOSq947TWXHzymKbinfZDaGST2HymhgReAgVNhjjT4JEF3FmjX4+tq6qt3B8R9wqLRmLNs4+aEkXyluZlHndEzfAVNs61zmsC56P7m4kNCgUYNAZQoiYphlyTkzk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712757620; c=relaxed/simple; bh=X2T9/6im6fX+kU9/Z4tPG9Rx1cuH7ekkKBiLwPpECEU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=TaxDJvgrwl2fBxJ59Tbf+RDG/7eYej8ZrQ9FEtieb9/cHUNvXMQDJ0jnR+w++2WdL+rbexniK/qR6Yzf9Yv8GVUcJroXSbXkhCXcCkdCk2QRQT07uYF2/eGI5TnotcvfAZWJciePHNdB7gWwhpR42+pQROOVqP2XMsFSBUlc4KU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fegQ3CO9; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="fegQ3CO9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9DDE3C433F1; Wed, 10 Apr 2024 14:00:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1712757620; bh=X2T9/6im6fX+kU9/Z4tPG9Rx1cuH7ekkKBiLwPpECEU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=fegQ3CO9RVfuDhv50USvMf/NWXuaO4FBE4zgHKwL2I6xQMUsrYWQEKQUgIhIkM6/r vwP7NIir6MYiqhUkh62e5pEabN4wptOuKHGCpUgM/dABEQqYGPPdxylu+UQ0njq/ui bvHqCtCBK1P7uuHKTcf1qGU+PdQivHleXQWfOroIy4NByha9JDvUjRZqVpH7E/LoU/ XiWKCBFOfSpxriFQKqUabQqj7fDD7ZFFJnOHLEw9M7FUp9NPKeJtQB8KHfwHfStujm ZoXBIrAB1fg10DVpOXiZ+AZVg5PjagnncQgLqmGfKrsJeQMaUWLj+vfBHo1qnvB6Um YoOIYtcmAB8TQ== Date: Wed, 10 Apr 2024 16:00:17 +0200 From: Frederic Weisbecker To: Sebastian Andrzej Siewior Cc: linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, Adrian Hunter , Alexander Shishkin , Arnaldo Carvalho de Melo , Ian Rogers , Ingo Molnar , Jiri Olsa , Marco Elver , Mark Rutland , Namhyung Kim , Peter Zijlstra , Thomas Gleixner , Arnaldo Carvalho de Melo Subject: Re: [PATCH v3 2/4] perf: Enqueue SIGTRAP always via task_work. Message-ID: References: <20240322065208.60456-1-bigeasy@linutronix.de> <20240322065208.60456-3-bigeasy@linutronix.de> <20240409085732.FBItbOSO@linutronix.de> <20240409134729.JpcBYOsK@linutronix.de> <20240410134702.dcWYciZB@linutronix.de> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20240410134702.dcWYciZB@linutronix.de> Le Wed, Apr 10, 2024 at 03:47:02PM +0200, Sebastian Andrzej Siewior a écrit : > On 2024-04-10 13:37:05 [+0200], Frederic Weisbecker wrote: > > > Couldn't we either flush _or_ remove the task_work in perf_release()? > > > > Right so the problem in perf_release() is that we may be dealing with task works > > of other tasks than current. In that case, task_work_cancel() is fine if it > > successes. But if it fails, you don't have the guarantee that the task work > > isn't concurrently running or about to run. And you have no way to know about > > that. So then you need some sort of flushing indeed. > > Since perf_release() preemptible, a wait/sleep for completion would be > best (instead of flushing). Like this then? https://lore.kernel.org/all/202403310406.TPrIela8-lkp@intel.com/T/#m63c28147d8ac06b21c64d7784d49f892e06c0e50 > > Thanks. > > > > > > Thanks. > > Sebastian