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Date: Fri, 31 Jul 2009 16:01:04 +0200
From: stephane eranian <eranian@...glemail.com>
To: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Oleg Nesterov <oleg@...hat.com>, Ingo Molnar <mingo@...e.hu>,
LKML <linux-kernel@...r.kernel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Thomas Gleixner <tglx@...utronix.de>,
Robert Richter <robert.richter@....com>,
Paul Mackerras <paulus@...ba.org>,
Andi Kleen <andi@...stfloor.org>,
Maynard Johnson <mpjohn@...ibm.com>,
Carl Love <cel@...ibm.com>,
Corey J Ashford <cjashfor@...ibm.com>,
Philip Mucci <mucci@...s.utk.edu>,
Dan Terpstra <terpstra@...s.utk.edu>,
perfmon2-devel <perfmon2-devel@...ts.sourceforge.net>,
Michael Kerrisk <mtk.manpages@...glemail.com>,
roland <roland@...hat.com>
Subject: Re: [RFC][PATCH] fcntl: F_[SG]ETOWN_TID
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@...llo.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@...llo.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:
>
>
>
--
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