Messages in this thread Patch in this message | | | Date | Fri, 31 Jul 2009 16:01:04 +0200 | Subject | Re: [RFC][PATCH] fcntl: F_[SG]ETOWN_TID | From | stephane eranian <> |
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Hi,
I have tried this patch in 2.6.30 and perfmon given I already had a stress test program for this problem. I can report that the patch seems to work for me.
This is a self-sampling multi-threaded program in which each thread also uses setitimer(ITIMER_REAL) and thus is getting SIGALRM.
First run with stock F_SETOWN:
$ self_smpl_multi 8 20000000 29 0 program_time = 8, threshold = 20000000, signum = 29 fcntl(F_SETOWN)
launch main: fd: 3, tid: 5836, self: 0x7f75f43206e0 launch side: fd: 4, tid: 5837, self: 0x40b59950 1: fd = 3, count = 30, iter = 651, rate = 46/Kiter 1: fd = 4, count = 29, iter = 623, rate = 46/Kiter (bad thread) ser = 287, fd = 4, tid = 5836, self = 0x7f75f43206e0 2: fd = 4, count = 119, iter = 2540, rate = 46/Kiter 2: fd = 3, count = 118, iter = 2510, rate = 47/Kiter (bad thread) ser = 330, fd = 4, tid = 5836, self = 0x7f75f43206e0 (bad thread) ser = 395, fd = 4, tid = 5836, self = 0x7f75f43206e0
The "(bad thread)" message shows up when the signal goes to the wrong thread.
Second run with F_SETOWN_TID:
$ ./self_smpl_multi 8 20000000 29 1 program_time = 8, threshold = 20000000, signum = 29 fcntl(F_SETOWN_TID)
launch main: fd: 3, tid: 5838, self: 0x7fa1800af6e0 launch side: fd: 4, tid: 5839, self: 0x4253a950 1: fd = 4, count = 52, iter = 1115, rate = 46/Kiter 1: fd = 3, count = 52, iter = 1115, rate = 46/Kiter 2: fd = 4, count = 119, iter = 2541, rate = 46/Kiter 2: fd = 3, count = 117, iter = 2490, rate = 46/Kiter 3: fd = 3, count = 114, iter = 2427, rate = 46/Kiter 3: fd = 4, count = 119, iter = 2541, rate = 46/Kiter 4: fd = 4, count = 119, iter = 2541, rate = 46/Kiter 4: fd = 3, count = 114, iter = 2428, rate = 46/Kiter 5: fd = 4, count = 119, iter = 2541, rate = 46/Kiter
No more error messages.
Thanks.
On Fri, Jul 31, 2009 at 10:35 AM, Peter Zijlstra<a.p.zijlstra@chello.nl> wrote: > In order to direct the SIGIO signal to a particular thread of a > multi-threaded application we cannot, like suggested by the manpage, put > a TID into the regular fcntl(F_SETOWN) call. It will still be send to > the whole process of which that thread is part. > > Since people do want to properly direct SIGIO we introduce F_SETOWN_TID, > which functions similarly to F_SETOWN, except positive arguments are > interpreted as TIDs and negative arguments are interpreted as PIDs. > > This extension is fully bug compatible with the old F_GETOWN > implementation in that F_GETOWN_TID will be troubled by the negative > return value for PIDs similarly to F_GETOWN's trouble with process > groups. > > [ compile tested only so far ] > > Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> > --- > arch/parisc/include/asm/fcntl.h | 2 + > fs/fcntl.c | 64 +++++++++++++++++++++++++++++++++----- > include/asm-generic/fcntl.h | 4 ++ > include/linux/fs.h | 11 +++++- > net/socket.c | 2 +- > 5 files changed, 71 insertions(+), 12 deletions(-) > > diff --git a/arch/parisc/include/asm/fcntl.h b/arch/parisc/include/asm/fcntl.h > index 1e1c824..5d5235a 100644 > --- a/arch/parisc/include/asm/fcntl.h > +++ b/arch/parisc/include/asm/fcntl.h > @@ -28,6 +28,8 @@ > #define F_SETOWN 12 /* for sockets. */ > #define F_SETSIG 13 /* for sockets. */ > #define F_GETSIG 14 /* for sockets. */ > +#define F_GETOWN_TID 15 > +#define F_SETOWN_TID 16 > > /* for posix fcntl() and lockf() */ > #define F_RDLCK 01 > diff --git a/fs/fcntl.c b/fs/fcntl.c > index ae41308..8d0b7f9 100644 > --- a/fs/fcntl.c > +++ b/fs/fcntl.c > @@ -197,13 +197,15 @@ static int setfl(int fd, struct file * filp, unsigned long arg) > } > > static void f_modown(struct file *filp, struct pid *pid, enum pid_type type, > - int force) > + int flags) > { > write_lock_irq(&filp->f_owner.lock); > - if (force || !filp->f_owner.pid) { > + if ((flags & FF_SETOWN_FORCE) || !filp->f_owner.pid) { > put_pid(filp->f_owner.pid); > filp->f_owner.pid = get_pid(pid); > filp->f_owner.pid_type = type; > + filp->f_owner.task_only = > + (type == PIDTYPE_PID && (flags & FF_SETOWN_TID)); > > if (pid) { > const struct cred *cred = current_cred(); > @@ -215,7 +217,7 @@ static void f_modown(struct file *filp, struct pid *pid, enum pid_type type, > } > > int __f_setown(struct file *filp, struct pid *pid, enum pid_type type, > - int force) > + int flags) > { > int err; > > @@ -223,12 +225,12 @@ int __f_setown(struct file *filp, struct pid *pid, enum pid_type type, > if (err) > return err; > > - f_modown(filp, pid, type, force); > + f_modown(filp, pid, type, flags); > return 0; > } > EXPORT_SYMBOL(__f_setown); > > -int f_setown(struct file *filp, unsigned long arg, int force) > +int f_setown(struct file *filp, unsigned long arg, int flags) > { > enum pid_type type; > struct pid *pid; > @@ -241,7 +243,7 @@ int f_setown(struct file *filp, unsigned long arg, int force) > } > rcu_read_lock(); > pid = find_vpid(who); > - result = __f_setown(filp, pid, type, force); > + result = __f_setown(filp, pid, type, flags); > rcu_read_unlock(); > return result; > } > @@ -263,6 +265,40 @@ pid_t f_getown(struct file *filp) > return pid; > } > > +static int f_setown_tid(struct file *filp, unsigned long arg) > +{ > + int flags = FF_SETOWN_FORCE; > + struct pid *pid; > + int who = arg; > + int ret = 0; > + > + if (who < 0) > + who = -who; > + else > + flags |= FF_SETOWN_TID; > + > + rcu_read_lock(); > + pid = find_vpid(who); > + ret = __f_setown(filp, pid, PIDTYPE_PID, flags); > + rcu_read_unlock(); > + > + return ret; > +} > + > +static pid_t f_getown_tid(struct file *filp) > +{ > + pid_t tid; > + > + read_lock(&filp->f_owner.lock); > + tid = pid_vnr(filp->f_owner.pid); > + if (filp->f_owner.pid_type == PIDTYPE_PGID) > + tid = 0; > + if (!filp->f_owner.task_only) > + tid = -tid; > + read_unlock(&filp->f_owner.lock); > + return tid; > +} > + > static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, > struct file *filp) > { > @@ -311,7 +347,14 @@ static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, > force_successful_syscall_return(); > break; > case F_SETOWN: > - err = f_setown(filp, arg, 1); > + err = f_setown(filp, arg, FF_SETOWN_FORCE); > + break; > + case F_GETOWN_TID: > + err = f_getown_tid(filp); > + force_successful_syscall_return(); > + break; > + case F_SETOWN_TID: > + err = f_setown_tid(filp, arg); > break; > case F_GETSIG: > err = filp->f_owner.signum; > @@ -431,6 +474,7 @@ static void send_sigio_to_task(struct task_struct *p, > int fd, > int reason) > { > + int (*send_sig)(int, struct siginfo *, struct task_struct *); > /* > * F_SETSIG can change ->signum lockless in parallel, make > * sure we read it once and use the same value throughout. > @@ -440,6 +484,8 @@ static void send_sigio_to_task(struct task_struct *p, > if (!sigio_perm(p, fown, signum)) > return; > > + send_sig = fown->task_only ? send_sig_info : group_send_sig_info; > + > switch (signum) { > siginfo_t si; > default: > @@ -461,11 +507,11 @@ static void send_sigio_to_task(struct task_struct *p, > else > si.si_band = band_table[reason - POLL_IN]; > si.si_fd = fd; > - if (!group_send_sig_info(signum, &si, p)) > + if (!send_sig(signum, &si, p)) > break; > /* fall-through: fall back on the old plain SIGIO signal */ > case 0: > - group_send_sig_info(SIGIO, SEND_SIG_PRIV, p); > + send_sig(SIGIO, SEND_SIG_PRIV, p); > } > } > > diff --git a/include/asm-generic/fcntl.h b/include/asm-generic/fcntl.h > index 4d3e483..d7906b8 100644 > --- a/include/asm-generic/fcntl.h > +++ b/include/asm-generic/fcntl.h > @@ -73,6 +73,10 @@ > #define F_SETSIG 10 /* for sockets. */ > #define F_GETSIG 11 /* for sockets. */ > #endif > +#ifndef F_SETOWN_TID > +#define F_SETOWN_TID 12 > +#define F_GETOWN_TID 13 > +#endif > > /* for F_[GET|SET]FL */ > #define FD_CLOEXEC 1 /* actually anything with low bit set goes */ > diff --git a/include/linux/fs.h b/include/linux/fs.h > index 0872372..42697e7 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -872,6 +872,7 @@ struct fown_struct { > rwlock_t lock; /* protects pid, uid, euid fields */ > struct pid *pid; /* pid or -pgrp where SIGIO should be sent */ > enum pid_type pid_type; /* Kind of process group SIGIO should be sent to */ > + bool task_only; /* task or group signal */ > uid_t uid, euid; /* uid/euid of process setting the owner */ > int signum; /* posix.1b rt signal to be delivered on IO */ > }; > @@ -1291,8 +1292,14 @@ extern void kill_fasync(struct fasync_struct **, int, int); > /* only for net: no internal synchronization */ > extern void __kill_fasync(struct fasync_struct *, int, int); > > -extern int __f_setown(struct file *filp, struct pid *, enum pid_type, int force); > -extern int f_setown(struct file *filp, unsigned long arg, int force); > +/* > + * setown flags > + */ > +#define FF_SETOWN_FORCE 1 > +#define FF_SETOWN_TID 2 > + > +extern int __f_setown(struct file *filp, struct pid *, enum pid_type, int flags); > +extern int f_setown(struct file *filp, unsigned long arg, int flags); > extern void f_delown(struct file *filp); > extern pid_t f_getown(struct file *filp); > extern int send_sigurg(struct fown_struct *fown); > diff --git a/net/socket.c b/net/socket.c > index 791d71a..ac57f8e 100644 > --- a/net/socket.c > +++ b/net/socket.c > @@ -916,7 +916,7 @@ static long sock_ioctl(struct file *file, unsigned cmd, unsigned long arg) > err = -EFAULT; > if (get_user(pid, (int __user *)argp)) > break; > - err = f_setown(sock->file, pid, 1); > + err = f_setown(sock->file, pid, FF_SETOWN_FORCE); > break; > case FIOGETOWN: > case SIOCGPGRP: > > > -- 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/
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