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Mon, 30 Jun 2025 14:29:36 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id okvhMFCfYmgZcQAAD6G6ig (envelope-from ); Mon, 30 Jun 2025 14:29:36 +0000 Date: Mon, 30 Jun 2025 16:30:18 +0200 From: Cyril Hrubis To: Andrea Cervesato Message-ID: References: <20250626-ioctl_pidfd_suite-v1-0-165b9abf0296@suse.com> <20250626-ioctl_pidfd_suite-v1-5-165b9abf0296@suse.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[99.99%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; MISSING_XM_UA(0.00)[]; TO_DN_SOME(0.00)[]; RCVD_TLS_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_THREE(0.00)[3]; FROM_EQ_ENVFROM(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.cz:email, imap1.dmz-prg2.suse.org:helo, yuki.lan:mid] X-Virus-Scanned: clamav-milter 1.0.7 at in-6.smtp.seeweb.it X-Virus-Status: Clean Subject: Re: [LTP] [PATCH 5/6] Add ioctl_pidfd03 test X-BeenThere: ltp@lists.linux.it X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux Test Project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: ltp@lists.linux.it Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ltp-bounces+ltp=archiver.kernel.org@lists.linux.it Sender: "ltp" Hi! > > If I'm reading the kernel code correctly, we should get the same result > > even before the pid was waited for, so we may as well do this check > > twice, once before the WAITPID() and once after the WAITPID(). > In this case, ESRCH is obtained only when info->mask == 0 __after__ > child has been reaped. > If child has not completed, we obtain the same result of the > ioctl_pidfd02 check before waitpid(). Sigh, right, I misread the kernel code again. We get ESRCH in the case of: - the target pid is not in our namespace or child namespace - task was reaped and PIDFD_INFO_EXIT was not set - task was reaped before we called get_task_cred() - task was reaped after we filled in data from task_cred (there is another check at the end of the function to make sure we do not return stale data) So I suppose that we can hit the first two, the second two are inherently racy. So after all with a pidfd pointing to a process in a child pid namespace we get all the uids/gids and pid filled in. Possibly changed by mappings, but I suppose these are going to be 1:1 since we haven't set any mapping tables. -- Cyril Hrubis chrubis@suse.cz -- Mailing list info: https://lists.linux.it/listinfo/ltp