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 623F625762; Wed, 14 Aug 2024 12:47:50 +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=1723639670; cv=none; b=QzlAvgxVU7vpTyrhU9nypUXD0Kb1aFjS5vHdL0/aFKe4xpKoelkp8xcmUoDksCGh8YqC2dN5uSr4e7fxjf718DthcNF3ur2AKEmByT1Tf0GtY/N9pYmrV8QVWNflsLAg2SuA7ILSRM3K3b4uDjFTrdMPrwKrAq26fpVhD3u0bfY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723639670; c=relaxed/simple; bh=cdea50Dx9ZmaxycbxHe2JgqHseZmZZXeTrngl7tmHJw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Bf6zqYTT5JsbQBgfB+wEjA044YPHaZkDXZmQSVVYQ9DqPt83EpjQWX9/x5yolEvJz0e9LS7o/Ww382DZhnKiEAcmA7LVEAaevJxoOqgjFzcXeJq3meEh+PIzNcYAhZdlQCDngUihH+CsYp4sVYAbbgmq6b7CBBrvHdikIrXxLfM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=N6LpNPa4; 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="N6LpNPa4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 73151C32786; Wed, 14 Aug 2024 12:47:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1723639669; bh=cdea50Dx9ZmaxycbxHe2JgqHseZmZZXeTrngl7tmHJw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=N6LpNPa4h9yx+mIwkZVdntlltbCAF+o+9SL23pQHh4oa8xy5LtZZ9hmryY6wXYrK2 kHwiXBQJsimkT3eR+oLI4vczahBQ+uwBCXEG98zCEqE69VB0h2MsP/9TsSBohPFAYI Sogmo7NuxX6fRf+ndyf+PMK7Gmxz3MSvLf2YjXcLh0Yvf6+E2lxMw8lHlVpgQmTDVE FU7UI5ynYEEiKXcuxLGcXP/IpK1P9RrqR9WmN+aajyq9nA/39f44lk0PaEjPL7yx9/ TQmAguxYYwUxiL27F6M8WIeQE8pJA/FJ/zwOKbCap/wGjUcYBZaMj5/il9P4y5tywk i8AYIJ5tdIjrQ== Date: Wed, 14 Aug 2024 14:47:46 +0200 From: Frederic Weisbecker To: neeraj.upadhyay@kernel.org Cc: rcu@vger.kernel.org, linux-kernel@vger.kernel.org, paulmck@kernel.org, joel@joelfernandes.org, boqun.feng@gmail.com, urezki@gmail.com, rostedt@goodmis.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, qiang.zhang1211@gmail.com, neeraj.iitr10@gmail.com Subject: Re: [PATCH 2/2] context_tracking: Invoke Tasks-RCU enter/exit for NMI context Message-ID: References: <20240807163506.434885-1-neeraj.upadhyay@kernel.org> <20240807163506.434885-3-neeraj.upadhyay@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@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: <20240807163506.434885-3-neeraj.upadhyay@kernel.org> Le Wed, Aug 07, 2024 at 10:05:06PM +0530, neeraj.upadhyay@kernel.org a écrit : > From: Neeraj Upadhyay > > rcu_task_enter() and rcu_task_exit() are not called on NMI > entry and exit. So, Tasks-RCU-Rude grace period wait is required to > ensure that NMI handlers have entered/exited into Tasks-RCU eqs. > For architectures which do not require Tasks-RCU-Rude (as the code > sections where RCU is not watching are marked as noinstr), when > those architectures switch to not using Tasks-RCU-Rude, NMI handlers > task exit to eqs will need to be handled correctly for Tasks-RCU holdout > tasks running on nohz_full CPUs. As it is safe to call these two > functions from NMI context, remove the in_nmi() check to ensure that > Tasks-RCU entry/exit is marked correctly for NMI handlers. > > Reported-by: Frederic Weisbecker > Suggested-by: Frederic Weisbecker > Suggested-by: "Paul E. McKenney" > Signed-off-by: Neeraj Upadhyay > --- > kernel/context_tracking.c | 6 ++---- > 1 file changed, 2 insertions(+), 4 deletions(-) > > diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c > index 152b485a62db..626dd7a173a5 100644 > --- a/kernel/context_tracking.c > +++ b/kernel/context_tracking.c > @@ -239,8 +239,7 @@ void noinstr ct_nmi_exit(void) > ct_kernel_exit_state(CT_RCU_WATCHING); > // ... but is no longer watching here. > > - if (!in_nmi()) > - rcu_task_exit(); > + rcu_task_exit(); And now since it is called by all callers of ct_kernel_exit_state(), you can call it from it directly. > } > > /** > @@ -273,8 +272,7 @@ void noinstr ct_nmi_enter(void) > */ > if (!rcu_is_watching_curr_cpu()) { > > - if (!in_nmi()) > - rcu_task_enter(); > + rcu_task_enter(); > > // RCU is not watching here ... > ct_kernel_enter_state(CT_RCU_WATCHING); Ditto for ct_kernel_enter_state(). Thanks. > -- > 2.40.1 >