On 08 Apr 2015, at 02:31, Philip Guenther <guent...@gmail.com> wrote:
> On Tue, Apr 7, 2015 at 3:57 PM, Kanonenvogel <kanonenvogel....@gmail.com>
> wrote:
>> I have idea to modify falloc() function and related logic.
>> Now, after successful faclloc call, we have half-initialized struct file
>> object, protected by FIF_LARVAL flag.
>> I want to initialise struct file object within falloc() and then put it to
>> fd_ofiles array and filehead list. This modification
>> permits to avoid half-initialization state and remove FIF_LARVAL flag and
>> related logic.
>
> The hard case is blocking opens of fifos, as the underlying operation
> involves a change visible to another process and that therefore cannot
> be rolled back.
>
>
> Philip Guenther
Ok, I understood.
And what about make struct file more smp friendly? For example, make operations
under
f_iflags and f_flags atomic?
Index: kern/kern_descrip.c
===================================================================
RCS file: /cvs/src/sys/kern/kern_descrip.c,v
retrieving revision 1.116
diff -u -p -r1.116 kern_descrip.c
--- kern/kern_descrip.c 19 Jan 2015 01:19:17 -0000 1.116
+++ kern/kern_descrip.c 8 Apr 2015 09:21:19 -0000
@@ -61,6 +61,7 @@
#include <sys/event.h>
#include <sys/pool.h>
#include <sys/ktrace.h>
+#include <sys/atomic.h>
#include <sys/pipe.h>
@@ -332,6 +333,7 @@ sys_fcntl(struct proc *p, void *v, regis
int i, tmp, newmin, flg = F_POSIX;
struct flock fl;
int error = 0;
+ int oflag, nflag;
restart:
if ((fp = fd_getfile(fdp, fd)) == NULL)
@@ -384,8 +386,12 @@ restart:
break;
case F_SETFL:
- fp->f_flag &= ~FCNTLFLAGS;
- fp->f_flag |= FFLAGS((long)SCARG(uap, arg)) & FCNTLFLAGS;
+ do {
+ oflag = fp->f_flag;
+ nflag = oflag & ~FCNTLFLAGS;
+ nflag |= FFLAGS((long)SCARG(uap, arg)) & FCNTLFLAGS;
+ } while (atomic_cas_uint(&fp->f_flag, oflag, nflag) != oflag);
+
tmp = fp->f_flag & FNONBLOCK;
error = (*fp->f_ops->fo_ioctl)(fp, FIONBIO, (caddr_t)&tmp, p);
if (error)
@@ -394,7 +400,7 @@ restart:
error = (*fp->f_ops->fo_ioctl)(fp, FIOASYNC, (caddr_t)&tmp, p);
if (!error)
break;
- fp->f_flag &= ~FNONBLOCK;
+ atomic_clearbits_int(&fp->f_flag, FNONBLOCK);
tmp = 0;
(void) (*fp->f_ops->fo_ioctl)(fp, FIONBIO, (caddr_t)&tmp, p);
break;
@@ -1160,7 +1166,7 @@ sys_flock(struct proc *p, void *v, regis
lf.l_len = 0;
if (how & LOCK_UN) {
lf.l_type = F_UNLCK;
- fp->f_iflags &= ~FIF_HASLOCK;
+ atomic_clearbits_int(&fp->f_iflags, FIF_HASLOCK);
error = VOP_ADVLOCK(vp, (caddr_t)fp, F_UNLCK, &lf, F_FLOCK);
goto out;
}
@@ -1172,7 +1178,7 @@ sys_flock(struct proc *p, void *v, regis
error = EINVAL;
goto out;
}
- fp->f_iflags |= FIF_HASLOCK;
+ atomic_setbits_int(&fp->f_iflags, FIF_HASLOCK);
if (how & LOCK_NB)
error = VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf, F_FLOCK);
else
Index: kern/sys_generic.c
===================================================================
RCS file: /cvs/src/sys/kern/sys_generic.c,v
retrieving revision 1.96
diff -u -p -r1.96 sys_generic.c
--- kern/sys_generic.c 12 Feb 2015 22:27:04 -0000 1.96
+++ kern/sys_generic.c 8 Apr 2015 09:21:19 -0000
@@ -52,6 +52,7 @@
#include <sys/stat.h>
#include <sys/malloc.h>
#include <sys/poll.h>
+#include <sys/atomic.h>
#ifdef KTRACE
#include <sys/ktrace.h>
#endif
@@ -456,17 +457,17 @@ sys_ioctl(struct proc *p, void *v, regis
case FIONBIO:
if ((tmp = *(int *)data) != 0)
- fp->f_flag |= FNONBLOCK;
+ atomic_setbits_int(&fp->f_flag, FNONBLOCK);
else
- fp->f_flag &= ~FNONBLOCK;
+ atomic_clearbits_int(&fp->f_flag, FNONBLOCK);
error = (*fp->f_ops->fo_ioctl)(fp, FIONBIO, (caddr_t)&tmp, p);
break;
case FIOASYNC:
if ((tmp = *(int *)data) != 0)
- fp->f_flag |= FASYNC;
+ atomic_setbits_int(&fp->f_flag, FASYNC);
else
- fp->f_flag &= ~FASYNC;
+ atomic_clearbits_int(&fp->f_flag, FASYNC);
error = (*fp->f_ops->fo_ioctl)(fp, FIOASYNC, (caddr_t)&tmp, p);
break;
Index: kern/uipc_usrreq.c
===================================================================
RCS file: /cvs/src/sys/kern/uipc_usrreq.c,v
retrieving revision 1.79
diff -u -p -r1.79 uipc_usrreq.c
--- kern/uipc_usrreq.c 11 Dec 2014 19:21:57 -0000 1.79
+++ kern/uipc_usrreq.c 8 Apr 2015 09:21:19 -0000
@@ -884,11 +884,11 @@ unp_gc(void)
unp_gcing = 1;
unp_defer = 0;
LIST_FOREACH(fp, &filehead, f_list)
- fp->f_iflags &= ~(FIF_MARK|FIF_DEFER);
+ atomic_clearbits_int(&fp->f_iflags, FIF_MARK|FIF_DEFER);
do {
LIST_FOREACH(fp, &filehead, f_list) {
if (fp->f_iflags & FIF_DEFER) {
- fp->f_iflags &= ~FIF_DEFER;
+ atomic_clearbits_int(&fp->f_iflags, FIF_DEFER);
unp_defer--;
} else {
if (fp->f_count == 0)
@@ -898,7 +898,7 @@ unp_gc(void)
if (fp->f_count == fp->f_msgcount)
continue;
}
- fp->f_iflags |= FIF_MARK;
+ atomic_setbits_int(&fp->f_iflags, FIF_MARK);
if (fp->f_type != DTYPE_SOCKET ||
(so = fp->f_data) == NULL)
@@ -1040,9 +1040,9 @@ unp_mark(struct file *fp)
if (fp->f_type == DTYPE_SOCKET) {
unp_defer++;
- fp->f_iflags |= FIF_DEFER;
+ atomic_setbits_int(&fp->f_iflags, FIF_DEFER);
} else {
- fp->f_iflags |= FIF_MARK;
+ atomic_setbits_int(&fp->f_iflags, FIF_MARK);
}
}
Index: kern/vfs_syscalls.c
===================================================================
RCS file: /cvs/src/sys/kern/vfs_syscalls.c,v
retrieving revision 1.216
diff -u -p -r1.216 vfs_syscalls.c
--- kern/vfs_syscalls.c 16 Dec 2014 18:30:04 -0000 1.216
+++ kern/vfs_syscalls.c 8 Apr 2015 09:21:19 -0000
@@ -901,7 +901,7 @@ doopenat(struct proc *p, int fd, const c
goto out;
}
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p);
- fp->f_iflags |= FIF_HASLOCK;
+ atomic_setbits_int(&fp->f_iflags, FIF_HASLOCK);
}
if (localtrunc) {
if ((fp->f_flag & FWRITE) == 0)
@@ -1083,7 +1083,7 @@ sys_fhopen(struct proc *p, void *v, regi
goto bad;
}
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p);
- fp->f_iflags |= FIF_HASLOCK;
+ atomic_setbits_int(&fp->f_iflags, FIF_HASLOCK);
}
VOP_UNLOCK(vp, 0, p);
*retval = indx;
Index: sys/file.h
===================================================================
RCS file: /cvs/src/sys/sys/file.h,v
retrieving revision 1.34
diff -u -p -r1.34 file.h
--- sys/file.h 18 Nov 2014 15:16:35 -0000 1.34
+++ sys/file.h 8 Apr 2015 09:21:23 -0000
@@ -63,7 +63,7 @@ struct fileops {
*/
struct file {
LIST_ENTRY(file) f_list;/* list of active files */
- short f_flag; /* see fcntl.h */
+ volatile int f_flag; /* see fcntl.h */
#define DTYPE_VNODE 1 /* file */
#define DTYPE_SOCKET 2 /* communications endpoint */
#define DTYPE_PIPE 3 /* pipe */
@@ -77,7 +77,7 @@ struct file {
struct fileops *f_ops;
off_t f_offset;
void *f_data; /* private data */
- int f_iflags; /* internal flags */
+ volatile int f_iflags; /* internal flags */
u_int64_t f_rxfer; /* total number of read transfers */
u_int64_t f_wxfer; /* total number of write transfers */
u_int64_t f_seek; /* total independent seek operations */
@@ -96,9 +96,9 @@ struct file {
#define FREF(fp) do { (fp)->f_count++; } while (0)
#define FRELE(fp,p) (--(fp)->f_count == 0 ? fdrop(fp, p) : 0)
-#define FILE_SET_MATURE(fp,p) do { \
- (fp)->f_iflags &= ~FIF_LARVAL; \
- FRELE(fp, p); \
+#define FILE_SET_MATURE(_fp, _p) do { \
+ atomic_clearbits_int(&(_fp)->f_iflags, FIF_LARVAL); \
+ FRELE(_fp, _p); \
} while (0)
int fdrop(struct file *, struct proc *);
