From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-184.mta1.migadu.com (out-184.mta1.migadu.com [95.215.58.184]) (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 AE2A113AA2E for ; Wed, 5 Mar 2025 01:36:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.184 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741138586; cv=none; b=dcTsDUEGHLFvSdD3gb5Nw9ee/0ywa9mH73oOoqHb/VV/NE5VbuVPvEBvnUevEuxdtUmUKtqUG/kA1ABOBFsfJJ7ug8UXpq6WJx+oOPLFacqdFtac8KAIKNDXQWb8QOt4k84vlM7euGQ9pRElxYkJkFtJ/cuvHAo8DOBUndI/P7c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741138586; c=relaxed/simple; bh=TJPyH+gD3BQboOZnrQdHUE8MCY+GRYwqfHzs4ORkRmE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=TDSpktcURdGp0KmPWWeDiW7jARLRKDLk/+hnj9ksr1YbEFkqQLCYFye1J9rtIE8x2CHsWkTWzb6IUyuyXsIFbxfatak4x5rJSQvppERkaiEqeyeAqRcyW3wRSqxYV9LeoRstODV5Yx/p81Q/qzKSrH1tVrrmMgUs1o406S8edv0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=jbouURjl; arc=none smtp.client-ip=95.215.58.184 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="jbouURjl" Message-ID: <716c1a2d-f4fb-407f-b77d-03019e0dd2a5@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1741138581; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=pAgdv4FIdU+D6X/ZKT+V/A2GWtawi5z/1zlXFT6xdeE=; b=jbouURjlivSM1EAeuj4aeHbt2ccTztdNhYBLzsWNLV1AMruNjyUuNdmw3expSqo/ouNTld 32ChbAY8k6gHfAgMXLwtp24A+Qfu3V/0UfcVgjXGy98iOIgIEjhQqgEVo3Tr+f8ICkQHVt n2EO6deQ8saLumVqwneuNV693iz5tjY= Date: Tue, 4 Mar 2025 17:36:14 -0800 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH bpf-next v4 3/3] selftests/bpf: Fix dangling stdout seen by traffic monitor thread To: Amery Hung Cc: daniel@iogearbox.net, andrii@kernel.org, alexei.starovoitov@gmail.com, martin.lau@kernel.org, kernel-team@meta.com, bpf@vger.kernel.org References: <20250304163626.1362031-1-ameryhung@gmail.com> <20250304163626.1362031-3-ameryhung@gmail.com> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Martin KaFai Lau In-Reply-To: <20250304163626.1362031-3-ameryhung@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT On 3/4/25 8:36 AM, Amery Hung wrote: > diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c > index ab0f2fed3c58..5b89f6ca5a0a 100644 > --- a/tools/testing/selftests/bpf/test_progs.c > +++ b/tools/testing/selftests/bpf/test_progs.c > @@ -88,7 +88,11 @@ static void stdio_hijack(char **log_buf, size_t *log_cnt) > #endif > } > > -static void stdio_restore_cleanup(void) > +static pthread_mutex_t stdout_lock = PTHREAD_MUTEX_INITIALIZER; > + > +static bool in_crash_handler(void); > + > +static void stdio_restore(void) > { > #ifdef __GLIBC__ > if (verbose() && env.worker_id == -1) { > @@ -98,34 +102,34 @@ static void stdio_restore_cleanup(void) > > fflush(stdout); > > - if (env.subtest_state) { > + pthread_mutex_lock(&stdout_lock); > + > + if (!env.subtest_state || in_crash_handler()) { Can the stdio restore be done in the crash_handler() itself instead of having a special case here and adding another in_crash_handler()? Theoretically, the crash_handler() only needs to fflush(stdout /* whatever the current stdout is */) and... > + if (stdout == env.stdout_saved) > + goto out; > + > + fclose(env.test_state->stdout_saved); > + env.test_state->stdout_saved = NULL; > + stdout = env.stdout_saved; > + stderr = env.stderr_saved; ... restore std{out,err} = env.std{out,err}_saved. At the crash point, it does not make a big difference to fclose(evn.test_state->stdout_saved) or not? If the crash_handler() does not close the stdout that the traffic monitor might potentially be using, then crash_handler() does not need to take mutex, right? > + } else { > fclose(env.subtest_state->stdout_saved); > env.subtest_state->stdout_saved = NULL; > stdout = env.test_state->stdout_saved; > stderr = env.test_state->stdout_saved; > - } else { > - fclose(env.test_state->stdout_saved); > - env.test_state->stdout_saved = NULL; > } > +out: > + pthread_mutex_unlock(&stdout_lock); > #endif > } > [ ... ] > +static bool in_crash_handler(void) > +{ > + struct sigaction sigact; > + > + /* sa_handler will be cleared if invoked since crash_handler is > + * registered with SA_RESETHAND > + */ > + sigaction(SIGSEGV, NULL, &sigact); > + > + return sigact.sa_handler != crash_handler; > +} > +