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Wed, 15 May 2019 15:35:24 +0000 (UTC) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190515_083524_436496_F6A1665B X-CRM114-Status: GOOD ( 12.46 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, linux-mips@vger.kernel.org, dhowells@redhat.com, linux-kselftest@vger.kernel.org, sparclinux@vger.kernel.org, linux-api@vger.kernel.org, elena.reshetova@intel.com, linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, linux-xtensa@linux-xtensa.org, keescook@chromium.org, arnd@arndb.de, jannh@google.com, linux-m68k@lists.linux-m68k.org, viro@zeniv.linux.org.uk, luto@kernel.org, tglx@linutronix.de, linux-arm-kernel@lists.infradead.org, linux-parisc@vger.kernel.org, cyphar@cyphar.com, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, luto@amacapital.net, ebiederm@xmission.com, linux-alpha@vger.kernel.org, akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 05/15, Oleg Nesterov wrote: > > On 05/15, Christian Brauner wrote: > > > > +SYSCALL_DEFINE2(pidfd_open, pid_t, pid, unsigned int, flags) > > +{ > > + int fd, ret; > > + struct pid *p; > > + struct task_struct *tsk; > > + > > + if (flags) > > + return -EINVAL; > > + > > + if (pid <= 0) > > + return -EINVAL; > > + > > + p = find_get_pid(pid); > > + if (!p) > > + return -ESRCH; > > + > > + rcu_read_lock(); > > + tsk = pid_task(p, PIDTYPE_PID); > > You do not need find_get_pid() before rcu_lock and put_pid() at the end. > You can just do find_vpid() under rcu_read_lock(). Ah, sorry. Somehow I forgot you need to call pidfd_create(pid), you can't do this under rcu_read_lock(). So I was wrong, you can't avoid get/put_pid. Oleg. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel