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 DD0E2184551; Mon, 12 Aug 2024 16:09:39 +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=1723478980; cv=none; b=dYVzPkOE9h+KJqN4daCHLIkRmJXDEH9pO6KukCEMKT7lM55ep9K7iQLmIntrEJpK2v/Z+xKg+oqVVkWUfCfMcSMYE2WD+8Rgx35+DIelkUkqUPAylvcj8cDDM2IU4TzuDUbi0xbyhRLexdxbtdw3EW3KmOvtORQOhgsoSw7f2ac= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723478980; c=relaxed/simple; bh=XEQFdZn0JcBv7lziDHtuupzEEgUzEa0OPsdy8jUBTSM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=MVJ+tR60bTI3HNeCJbFoaYb6eimO1Er2g+embY8acO5n4iEcZYqyuZWcyG1eBUCdutgy/VQ9aFdlMu3yi2hDSuHmMqEzZMShjFAzrAuRgjfUuWubR0W4U8IBTKPVM3XCSZ09RJin3MflPmaxT8QfvS3uZLdTTsd4MZDX3enRHrs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nvOSN8IN; 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="nvOSN8IN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 54AC1C4AF09; Mon, 12 Aug 2024 16:09:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1723478979; bh=XEQFdZn0JcBv7lziDHtuupzEEgUzEa0OPsdy8jUBTSM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=nvOSN8INE8dDYhypKFxDz1CqaVB2ZiqdiXe6+qpZijdlzK78wRUyShZhbrAdN88pJ DM8A4aTStnQFIq8GSeGb//g5SStVZ2vdVCRVcjB4+dkoWyODi7SWYh0evb6/fSxEFs KpCrh2LUuqrrw0+mmaoLMjqssIsLCm/xD9bppgU9DHmPeZC3gRLnuLGcbWqKgQ387V Emq9Bzqae+wlNktq/PQlT7bwaL1QDnAf2j6H2QhZWF4eKQDQ69ymJh4GPUl4ty6bBd 8qsqHa7ccoAZOQEBvSct/zpZcyZwOOxlmE3+ETgwznLkOeU0birpdOnn6btBlH8k6+ 8lOS8puX+WiXg== Date: Mon, 12 Aug 2024 13:09:36 -0300 From: Arnaldo Carvalho de Melo To: Namhyung Kim Cc: Ian Rogers , Kan Liang , Jiri Olsa , Adrian Hunter , Peter Zijlstra , Ingo Molnar , LKML , linux-perf-users@vger.kernel.org, Dan Carpenter Subject: Re: [PATCH] perf lock contention: Change stack_id type to s32 Message-ID: References: <909abbc8-efca-40df-9876-8c36b6942a83@stanley.mountain> <20240810191704.1948365-1-namhyung@kernel.org> 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=us-ascii Content-Disposition: inline In-Reply-To: <20240810191704.1948365-1-namhyung@kernel.org> On Sat, Aug 10, 2024 at 12:17:04PM -0700, Namhyung Kim wrote: > The bpf_get_stackid() helper returns a signed type to check whether it > failed to get a stacktrace or not. But it saved the result in u32 and > checked if the value is negative. > > 376 if (needs_callstack) { > 377 pelem->stack_id = bpf_get_stackid(ctx, &stacks, > 378 BPF_F_FAST_STACK_CMP | stack_skip); > --> 379 if (pelem->stack_id < 0) > > ./tools/perf/util/bpf_skel/lock_contention.bpf.c:379 contention_begin() > warn: unsigned 'pelem->stack_id' is never less than zero. > > Let's change the type to s32 instead. > > Fixes: 6d499a6b3d90 ("perf lock: Print the number of lost entries for BPF") Thanks, applied to perf-tools-next, - Arnaldo > Reported-by: Dan Carpenter > Signed-off-by: Namhyung Kim > --- > tools/perf/util/bpf_skel/lock_data.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/tools/perf/util/bpf_skel/lock_data.h b/tools/perf/util/bpf_skel/lock_data.h > index 36af11faad03..de12892f992f 100644 > --- a/tools/perf/util/bpf_skel/lock_data.h > +++ b/tools/perf/util/bpf_skel/lock_data.h > @@ -7,11 +7,11 @@ struct tstamp_data { > u64 timestamp; > u64 lock; > u32 flags; > - u32 stack_id; > + s32 stack_id; > }; > > struct contention_key { > - u32 stack_id; > + s32 stack_id; > u32 pid; > u64 lock_addr_or_cgroup; > }; > -- > 2.46.0.76.ge559c4bf1a-goog