Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754778AbZAFSdu (ORCPT ); Tue, 6 Jan 2009 13:33:50 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751882AbZAFSdk (ORCPT ); Tue, 6 Jan 2009 13:33:40 -0500 Received: from rcsinet13.oracle.com ([148.87.113.125]:60990 "EHLO rgminet13.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752015AbZAFSdj (ORCPT ); Tue, 6 Jan 2009 13:33:39 -0500 Message-ID: <4963A392.1060104@oracle.com> Date: Tue, 06 Jan 2009 10:31:46 -0800 From: Randy Dunlap Organization: Oracle Linux Engineering User-Agent: Thunderbird 2.0.0.6 (X11/20070801) MIME-Version: 1.0 To: Casey Dahlin CC: Linux Kernel Subject: Re: [RFC PATCH v2] waitfd References: <49639EB8.40204@redhat.com> In-Reply-To: <49639EB8.40204@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Source-IP: acsmt701.oracle.com [141.146.40.71] X-Auth-Type: Internal IP X-CT-RefId: str=0001.0A090202.4963A39B.0089:SCFSTAT928724,ss=1,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 11213 Lines: 367 Casey Dahlin wrote: > Linux now exposes signals, timers, and events via file descriptors > through signalfd, timerfd, and eventfd. This means programmers can use a > single select/[e]poll call to monitor all change in their program. This > patch aims to expose child death via the same mechanism. > > waitfd provides a file descriptor out of which may be read a series of > siginfo_t objects describing child death. A child process is reaped as > soon as its information is read. This means child monitoring too can be > performed with that same poll call. > > Patch is against v2.6.28 > > --CJD > > diff --git a/arch/x86/include/asm/unistd_32.h > b/arch/x86/include/asm/unistd_32.h > index f2bba78..134d83c 100644 > --- a/arch/x86/include/asm/unistd_32.h > +++ b/arch/x86/include/asm/unistd_32.h > @@ -338,6 +338,7 @@ > #define __NR_dup3 330 > #define __NR_pipe2 331 > #define __NR_inotify_init1 332 > +#define __NR_waitfd 333 > > #ifdef __KERNEL__ > > diff --git a/arch/x86/include/asm/unistd_64.h > b/arch/x86/include/asm/unistd_64.h > index d2e415e..b28eb07 100644 > --- a/arch/x86/include/asm/unistd_64.h > +++ b/arch/x86/include/asm/unistd_64.h > @@ -653,6 +653,8 @@ __SYSCALL(__NR_dup3, sys_dup3) > __SYSCALL(__NR_pipe2, sys_pipe2) > #define __NR_inotify_init1 294 > __SYSCALL(__NR_inotify_init1, sys_inotify_init1) > +#define __NR_waitfd 295 > +__SYSCALL(__NR_waitfd, sys_waitfd) > Only for x86?? > > #ifndef __NO_STUBS > diff --git a/arch/x86/kernel/syscall_table_32.S > b/arch/x86/kernel/syscall_table_32.S > index d44395f..c796a8b 100644 > --- a/arch/x86/kernel/syscall_table_32.S > +++ b/arch/x86/kernel/syscall_table_32.S > @@ -332,3 +332,4 @@ ENTRY(sys_call_table) > .long sys_dup3 /* 330 */ > .long sys_pipe2 > .long sys_inotify_init1 > + .long sys_waitfd > diff --git a/fs/Makefile b/fs/Makefile > index d9f8afe..74c31fb 100644 > --- a/fs/Makefile > +++ b/fs/Makefile > @@ -25,6 +25,7 @@ obj-$(CONFIG_INOTIFY_USER) += inotify_user.o > obj-$(CONFIG_EPOLL) += eventpoll.o > obj-$(CONFIG_ANON_INODES) += anon_inodes.o > obj-$(CONFIG_SIGNALFD) += signalfd.o > +obj-$(CONFIG_WAITFD) += waitfd.o > obj-$(CONFIG_TIMERFD) += timerfd.o > obj-$(CONFIG_EVENTFD) += eventfd.o > obj-$(CONFIG_AIO) += aio.o > diff --git a/fs/waitfd.c b/fs/waitfd.c > new file mode 100644 > index 0000000..0155a83 > --- /dev/null > +++ b/fs/waitfd.c > @@ -0,0 +1,117 @@ > +/* > + * fs/waitfd.c > + * > + * Copyright (C) 2008 Red Hat, Casey Dahlin > + * > + * Largely derived from fs/signalfd.c > + */ > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +long do_waitid(int which, pid_t upid, > + struct siginfo __user *infop, int options, > + struct rusage __user *ru); > + > +struct waitfd_ctx { > + int ops; > + int which; > + pid_t upid; > +}; > + Please use kernel coding style: use tabs to indent, not , and struct members, functions, etc., are indented by one tab stop minimum. > +static int waitfd_release(struct inode *inode, struct file *file) > +{ > + kfree(file->private_data); > + return 0; > +} > + > +static unsigned int waitfd_poll(struct file *file, poll_table *wait) > +{ > + struct waitfd_ctx *ctx = file->private_data; > + long value; > + > + poll_wait(file, ¤t->signal->wait_chldexit, wait); > + > + value = do_waitid(ctx->which, ctx->upid, NULL, > + ctx->ops | WNOHANG | WNOWAIT, NULL); > + if (value > 0 || value == -ECHILD) > + return POLLIN; > + > + return 0; > +} > + > +/* > + * Returns a multiple of the size of a struct siginfo, or a negative > + * error code. The "count" parameter must be at least sizeof(struct > siginfo) > + */ > +static ssize_t waitfd_read(struct file *file, char __user *buf, size_t > count, > + loff_t *ppos) > +{ > + struct waitfd_ctx *ctx = file->private_data; > + struct siginfo __user *info_addr = (struct siginfo *)buf; > + int flags = ctx->ops; > + ssize_t ret, total = 0; > + > + count /= sizeof(struct siginfo); > + if (!count) > + return -EINVAL; > + > + do { > + ret = do_waitid(ctx->which, ctx->upid, info_addr, flags, NULL); > + if (ret == 0) > + ret = -EAGAIN; > + if (ret == -ECHILD) > + ret = 0; > + if (ret <= 0) > + break; > + > + info_addr++; > + total += sizeof(struct siginfo); > + flags |= WNOHANG; > + } while (--count); > + > + return total ? total: ret; return total ? total : ret; please. > +} > + > +static const struct file_operations waitfd_fops = { > + .release = waitfd_release, > + .poll = waitfd_poll, > + .read = waitfd_read, > +}; > + > +asmlinkage long sys_waitfd(int which, pid_t upid, int options, int unused) > +{ > + int ufd; > + struct waitfd_ctx *ctx; > + > + /* Just to make sure we don't end up with a sys_waitfd4 */ > + (void)unused; > + > + if (options & ~(WNOHANG|WEXITED|WSTOPPED|WCONTINUED)) > + return -EINVAL; > + if (!(options & (WEXITED|WSTOPPED|WCONTINUED))) > + return -EINVAL; Use spaces around '|'. > + > + ctx = kmalloc(sizeof(*ctx), GFP_KERNEL); > + if (!ctx) > + return -ENOMEM; > + > + ctx->ops = options; > + ctx->upid = upid; > + ctx->which = which; > + > + ufd = anon_inode_getfd("[waitfd]", &waitfd_fops, ctx, > + (options & WNOHANG) ? O_NONBLOCK : 0); > + if (ufd < 0) > + kfree(ctx); > + > + return ufd; > +} > diff --git a/init/Kconfig b/init/Kconfig > index f763762..bc34871 100644 > --- a/init/Kconfig > +++ b/init/Kconfig > @@ -683,6 +683,16 @@ config EPOLL > Disabling this option will cause the kernel to be built without > support for epoll family of system calls. > > +config WAITFD > + bool "Enable waitfd() system call" if EMBEDDED > + select ANON_INODES > + default y > + help > + Enable the waitfd() system call that allows receving child state receiving Kconfig help text should be indented by . > + changes from a file descriptor. > + > + If unsure, say Y. > + > config SIGNALFD > bool "Enable signalfd() system call" if EMBEDDED > select ANON_INODES > diff --git a/kernel/exit.c b/kernel/exit.c > index 2d8be7e..b53e8ba 100644 > --- a/kernel/exit.c > +++ b/kernel/exit.c > @@ -1233,18 +1233,20 @@ static int wait_noreap_copyout(struct > task_struct *p, pid_t pid, uid_t uid, > int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0; > > put_task_struct(p); > - if (!retval) > - retval = put_user(SIGCHLD, &infop->si_signo); > - if (!retval) > - retval = put_user(0, &infop->si_errno); > - if (!retval) > - retval = put_user((short)why, &infop->si_code); > - if (!retval) > - retval = put_user(pid, &infop->si_pid); > - if (!retval) > - retval = put_user(uid, &infop->si_uid); > - if (!retval) > - retval = put_user(status, &infop->si_status); > + if (infop) { > + if (!retval) > + retval = put_user(SIGCHLD, &infop->si_signo); > + if (!retval) > + retval = put_user(0, &infop->si_errno); > + if (!retval) > + retval = put_user((short)why, &infop->si_code); > + if (!retval) > + retval = put_user(pid, &infop->si_pid); > + if (!retval) > + retval = put_user(uid, &infop->si_uid); > + if (!retval) > + retval = put_user(status, &infop->si_status); > + } > if (!retval) > retval = pid; > return retval; > @@ -1727,35 +1729,12 @@ repeat: > end: > current->state = TASK_RUNNING; > remove_wait_queue(¤t->signal->wait_chldexit,&wait); > - if (infop) { > - if (retval > 0) > - retval = 0; > - else { > - /* > - * For a WNOHANG return, clear out all the fields > - * we would set so the user can easily tell the > - * difference. > - */ > - if (!retval) > - retval = put_user(0, &infop->si_signo); > - if (!retval) > - retval = put_user(0, &infop->si_errno); > - if (!retval) > - retval = put_user(0, &infop->si_code); > - if (!retval) > - retval = put_user(0, &infop->si_pid); > - if (!retval) > - retval = put_user(0, &infop->si_uid); > - if (!retval) > - retval = put_user(0, &infop->si_status); > - } > - } > return retval; > } > > -asmlinkage long sys_waitid(int which, pid_t upid, > - struct siginfo __user *infop, int options, > - struct rusage __user *ru) > +long do_waitid(int which, pid_t upid, > + struct siginfo __user *infop, int options, > + struct rusage __user *ru) > { > struct pid *pid = NULL; > enum pid_type type; > @@ -1789,6 +1768,39 @@ asmlinkage long sys_waitid(int which, pid_t upid, > ret = do_wait(type, pid, options, infop, NULL, ru); > put_pid(pid); > > + return ret; > +} > + > +asmlinkage long sys_waitid(int which, pid_t upid, > + struct siginfo __user *infop, int options, > + struct rusage __user *ru) > +{ > + long ret; > + > + ret = do_waitid(which, upid, infop, options, ru); > + > + if (ret > 0) > + ret = 0; > + else { > + /* > + * For a WNOHANG return, clear out all the fields > + * we would set so the user can easily tell the > + * difference. > + */ > + if (!ret) > + ret = put_user(0, &infop->si_signo); > + if (!ret) > + ret = put_user(0, &infop->si_errno); > + if (!ret) > + ret = put_user(0, &infop->si_code); > + if (!ret) > + ret = put_user(0, &infop->si_pid); > + if (!ret) > + ret = put_user(0, &infop->si_uid); > + if (!ret) > + ret = put_user(0, &infop->si_status); > + } > + > /* avoid REGPARM breakage on x86: */ > asmlinkage_protect(5, ret, which, upid, infop, options, ru); > return ret; > diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c > index e14a232..e8d4da6 100644 > --- a/kernel/sys_ni.c > +++ b/kernel/sys_ni.c > @@ -163,6 +163,7 @@ cond_syscall(sys_ioprio_set); > cond_syscall(sys_ioprio_get); > > /* New file descriptors */ > +cond_syscall(sys_waitfd); > cond_syscall(sys_signalfd); > cond_syscall(sys_signalfd4); > cond_syscall(compat_sys_signalfd); -- ~Randy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/