From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 3A35439282D; Tue, 13 Jan 2026 13:56:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768312580; cv=none; b=T3hKHhUGqETEBZpk9Lg1nE7zUPd5Ai5/dKTz+gWbn2q8QPQtBb4SXY6Ko4kSI3RY0WBlniZT6/E28op5rjpaPTA9ACUh5M8Ssb/r9++W2dIxWkaQ7o+CLCqwIlQe4cYWb6lA/wtFarxnOh1qLsMN5wUlyfOtqXJ7F1Dbdq7rmr4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768312580; c=relaxed/simple; bh=VKDfdEeAGmvs2Itgr8lGNLNIeh7BO8p2bQkfzHAwiR8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=R8BE1VYtow3gJA4MGfr0gU8+B1bSttjW7ppBP7tL14cDrX+UlAzr01rafW/czylMkvxoGJy18BY1qVQRWvoQ5Im4cDPNdtfm2Nh8lx+katQG9c1iPn8UUaAbtAfayTSYTUK4Qqp+yMPaKt8ehHi9SoE0IQLz9YUkvmp0PL+2RBY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=n3FdTXzO; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=KTz2j3kb; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="n3FdTXzO"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="KTz2j3kb" Date: Tue, 13 Jan 2026 14:56:16 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1768312577; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Fw8ZcQHK/uDcyJYw+AZQbOaYuF1pprqHw9wHUqcLuEQ=; b=n3FdTXzOr0VKcJs3mJugN4aNportC8bdbjxNqO7ba9vZJxdHdwRyKe+viT5AsTnoWzP4YF oqQRgN6gTybyMkL/4aUU4ya2NayTmm2nW8oSLNieKc++ngmQzmjJe6zhiuLBf2QQu4pW8r rpg31t89AZ3ZP9Yv3/S8D4BInqi0rI1tS29MLkYMANSeJki4PLJ1djIw+ZFUqNHgoK2Rno 7asrBrydIiMLCi0nk1WcvC4ltvKse+bnbdGYiQZY8/mH6Wa47ew71GFqIjImrICvEA8H1D g6RpIzakTtDpFQfgBdn4BvlZty5I6vDStVOGzaoPmtDxw+MSsqEpOmIaspA1lQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1768312577; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Fw8ZcQHK/uDcyJYw+AZQbOaYuF1pprqHw9wHUqcLuEQ=; b=KTz2j3kbnZctHgmTGHQCuyw8vAtNT91E2iVL+4b4eizyLcSvwLI46I1F+EG3WQgxHhaJpu qG4MCb1qPNlf6NBg== From: Sebastian Andrzej Siewior To: Mathieu Desnoyers Cc: Steven Rostedt , LKML , Linux trace kernel , bpf@vger.kernel.org, Masami Hiramatsu , "Paul E. McKenney" , Thomas Gleixner Subject: Re: [PATCH v5] tracing: Guard __DECLARE_TRACE() use of __DO_TRACE_CALL() with SRCU-fast Message-ID: <20260113135616.xt2Nm4IY@linutronix.de> References: <20260108220550.2f6638f3@fedora> <20260109122142.108982d9@gandalf.local.home> <8252131c-4c54-43ca-9041-71481165e516@efficios.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <8252131c-4c54-43ca-9041-71481165e516@efficios.com> On 2026-01-09 13:58:21 [-0500], Mathieu Desnoyers wrote: > On 2026-01-09 12:21, Steven Rostedt wrote: > > > Using SRCU-fast to protect tracepoint callback iteration makes sense > > > for preempt-rt, but I'd recommend moving the migrate disable guard > > > within the bpf callback code rather than slowing down other tracers > > > which execute within a short amount of time. Other tracers can then > > > choose to disable preemption rather than migration if that's a better > > > fit for their needs. > > > > This is a discussion with the BPF folks. > > FWIW, the approach I'm proposing would be similar to what I've done for > faultable syscall tracepoints. I just started reading this thread but we could limit the migrate_disable() to only the BPF callback part so it does not effect the whole tracepoint if there not a BFP program attached to it. Sebastian