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charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: ericsson.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: AM8PR07MB7666.eurprd07.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: bddcb31b-9ed8-404f-a409-08daab5f385a X-MS-Exchange-CrossTenant-originalarrivaltime: 11 Oct 2022 08:04:28.2053 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 92e84ceb-fbfd-47ab-be52-080c6b87953f X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: Ak1d+nkpSaraHiq38AIb19Q4cweZ9nJ0j4EMPFxpGDPHBDBS6NoTgHHeNslieV+/mz9mfkbC+katqPBMtCAtNw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: AS8PR07MB8965 Precedence: bulk List-ID: X-Mailing-List: linux-perf-users@vger.kernel.org Although it's been a while I still think this is a bug. Assuming any posix = function, e.g. close() in record__terminate_thread(), can modify errno, it = seems like this is an issue which may produce confusing error messages. Wil= l there be a fix for this? See below. > -----Original Message----- > From: Emil Berg > Sent: den 29 juni 2022 07:32 > To: linux-perf-users@vger.kernel.org > Subject: Possible overwriting of errno >=20 > Hi! >=20 > I'm getting the error "Failed to start threads: File exists" from perf, p= robably > EEXIST. >=20 > I just want to discuss the changes to tools/perf/builtin-record.c made Fe= b 10 > 2022 with: > perf record: Start threads in the beginning of trace streaming > SHA: 3217e9fecf118d5dcabdd68d91e0c6afcb4c3e1b >=20 > At line 2014 pthread_create() is run and on line 2017 strerror(errno) is > printed. Between line 2014 and 2017 record__terminate_thread() is run. >=20 > I just think record__terminate_thread() run in-between looks like it may > overwrite errno, thus messing up the error message. To be clear I think t= he > error message should come from failure of thread creation and not from > failure of thread termination. Can someone enlighten me here? >=20 > if (pthread_create(&handle, &attrs, record__thread, &thread_data[t])) { > for (tt =3D 1; tt < t; tt++) > record__terminate_thread(&thread_data[t]); > pr_err("Failed to start threads: %s\n", strerror(errno)); >=20 > /Emil Berg