From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 2F2E4625 for ; Sat, 11 Jul 2026 01:20:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783732854; cv=none; b=RY+1vYZeMutmMEoGIMyKscHep04l7RmPFGo+GCjI0tcWfClDwK500zLhjGG6osOggKvG+Q7+K6YwyyeghmVrDThkcDCJuOzaf7wD3WG8jDUeWh30jDRfddefePOTbFBimCwsfYy3qH0tDcujFG3ygxmtrUJFBHjG2ce3THX1t0c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783732854; c=relaxed/simple; bh=1jD4MALjBIDTTS0jbSIFlhwwyoxJEfge8MT7KRGUzfo=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=j9HRxwFhQ7Hs6yHaEt6hLZi66PVl5CkTElpXCYAenYIcmOqZPYg1x/wphIisJ4PKhIkHRZpNBYRDqqUgzTZ4B11JvXAUDvyyavST8BzC0Cifnv0ujm+YqtM586gABdNGGlJ+bbpZ0lm9lsBfVjp2tY3JFboelNI1p43QStB0yrk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=TDPKGsQx; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="TDPKGsQx" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EBE671F00A3A; Sat, 11 Jul 2026 01:20:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783732853; bh=7MZzoD1knuU9PyhdW5oHDHCiHoT126eAjNA/BNDzS5g=; h=Date:From:To:Cc:Subject:References; b=TDPKGsQx4RjXXU1J5AqeE4VdcfPqp6elgJG+JARbnqRdz5YwhQTuW3Bkr5EfMcmZp 6KaxnI3+zBFT7rYbG0zTHWlMF/Niz2N9ayCa8TfKV12tFcvkaUv+7QLfjo0ncM5gvs d8ckatVFKnAVMB+bDrQUPsVcrEUp3fL0eTeXeJLisP/8Z73h0NbwmGlXRqx3Jcw3K1 FDwKjSGCIMktuubxr6ezR0qvc6RPnofHLpALqt9lmkXzUiEP4PoVeQ8EgKZkDLUtLN SgytFE7UVt7vr80ETOQWJm/Hc4hM4mjg9JvUGLZxY2RBJfZTzarlrRAKjs/17CH4ly CiKm5DvDN8GIw== Received: from rostedt by gandalf with local (Exim 4.99.4) (envelope-from ) id 1wiMOt-00000002F2W-3Ih7; Fri, 10 Jul 2026 21:21:03 -0400 Message-ID: <20260711012103.636365268@kernel.org> User-Agent: quilt/0.69 Date: Fri, 10 Jul 2026 21:20:41 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , Michael Bommarito Subject: [for-linus][PATCH 1/4] selftests/user_events: Wait for deferred event teardown after unregister References: <20260711012040.762290323@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=UTF-8 From: Michael Bommarito Unregistering a user event now defers the drop of the enabler's event reference (and the freeing of the enabler) past an RCU grace period. As a result DIAG_IOCSDEL can transiently fail with -EBUSY while that last reference is still being dropped, where it previously succeeded immediately. Two tests assumed the delete takes effect the instant the unregister returns: - abi_test "flags" deletes the event right after disabling it. - perf_test's fixture teardown clear() deletes __test_event before the next test registers the same name; a stale event makes the following registration fail with -EADDRINUSE. Retry the delete until it succeeds (or the event is already gone) with a bounded wait, matching the existing wait_for_delete() idiom in the same suite, so the tests are robust to the deferred teardown. Link: https://patch.msgid.link/20260707180240.2887081-1-michael.bommarito@gmail.com Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Michael Bommarito Signed-off-by: Steven Rostedt --- .../testing/selftests/user_events/abi_test.c | 29 ++++++++++++++++++- .../testing/selftests/user_events/perf_test.c | 26 +++++++++++++++-- 2 files changed, 51 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/user_events/abi_test.c b/tools/testing/selftests/user_events/abi_test.c index 85892b3b719c..b71813eaf5c0 100644 --- a/tools/testing/selftests/user_events/abi_test.c +++ b/tools/testing/selftests/user_events/abi_test.c @@ -132,6 +132,33 @@ static int event_delete(void) return ret; } +/* + * Deleting an event drops its last reference, but an unregister may defer + * that put (and the freeing of the associated enabler) past an RCU grace + * period. The delete can therefore transiently fail with -EBUSY while the + * previous reference is still being dropped. Retry only on that transient + * failure; treat an already-deleted event (-ENOENT) as success and return + * any other error immediately rather than spinning for the full timeout. + */ +static int wait_for_event_delete(void) +{ + int i, ret; + + for (i = 0; i < 10000; ++i) { + ret = event_delete(); + + if (ret == 0 || errno == ENOENT) + return 0; + + if (errno != EBUSY) + return ret; + + usleep(1000); + } + + return ret; +} + static int reg_enable_multi(void *enable, int size, int bit, int flags, char *args) { @@ -262,7 +289,7 @@ TEST_F(user, flags) { ASSERT_TRUE(event_exists()); /* Ensure we can delete it */ - ASSERT_EQ(0, event_delete()); + ASSERT_EQ(0, wait_for_event_delete()); /* USER_EVENT_REG_MAX or above is not allowed */ ASSERT_EQ(-1, reg_enable_flags(&self->check, sizeof(int), 0, diff --git a/tools/testing/selftests/user_events/perf_test.c b/tools/testing/selftests/user_events/perf_test.c index cafec0e52eb3..5727cb5b914c 100644 --- a/tools/testing/selftests/user_events/perf_test.c +++ b/tools/testing/selftests/user_events/perf_test.c @@ -85,6 +85,7 @@ static int get_offset(void) static int clear(int *check) { struct user_unreg unreg = {0}; + int i, ret; unreg.size = sizeof(unreg); unreg.disable_bit = 31; @@ -99,13 +100,32 @@ static int clear(int *check) if (errno != ENOENT) return -1; - if (ioctl(fd, DIAG_IOCSDEL, "__test_event") == -1) - if (errno != ENOENT) + /* + * Deleting the event drops its last reference, but the unregister + * above defers that put (and the freeing of the enabler) past an RCU + * grace period. The delete can therefore transiently fail with -EBUSY + * until that reference is dropped. Retry for up to ~10 seconds so the + * event is actually gone before the next test registers the same name. + */ + for (i = 0; i < 10000; ++i) { + ret = ioctl(fd, DIAG_IOCSDEL, "__test_event"); + + if (ret == 0 || errno == ENOENT) { + ret = 0; + break; + } + + if (errno != EBUSY) { + close(fd); return -1; + } + + usleep(1000); + } close(fd); - return 0; + return ret; } FIXTURE(user) { -- 2.53.0