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- Add a lock for protecting against msleep(bp, ...) wakeup(bp) races.

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- Create a new function bdone() which sets B_DONE and calls wakup(bp). This
   is suitable for use as b_iodone for buf consumers who are not going
   through the buf cache.
 - Create a new function bwait() which waits for the buf to be done at a set
   priority and with a specific wmesg.
 - Replace several cases where the above functionality was implemented
   without locking with the new functions.
This commit is contained in:
Jeff Roberson 2003-03-13 07:31:45 +00:00
parent e99215a614
commit 749ffa4ecd
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=112183
4 changed files with 46 additions and 36 deletions
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19
sys/fs/specfs/spec_vnops.c
View File

@ -123,8 +123,6 @@ spec_vnoperate(ap)
return (VOCALL(spec_vnodeop_p, ap->a_desc->vdesc_offset, ap));
}
static void spec_getpages_iodone(struct buf *bp);
/*
* Open a special file.
*/
@ -689,15 +687,6 @@ spec_advlock(ap)
return (ap->a_flags & F_FLOCK ? EOPNOTSUPP : EINVAL);
}
static void
spec_getpages_iodone(bp)
struct buf *bp;
{
bp->b_flags |= B_DONE;
wakeup(bp);
}
static int
spec_getpages(ap)
struct vop_getpages_args *ap;
@ -755,7 +744,7 @@ spec_getpages(ap)
/* Build a minimal buffer header. */
bp->b_iocmd = BIO_READ;
bp->b_iodone = spec_getpages_iodone;
bp->b_iodone = bdone;
/* B_PHYS is not set, but it is nice to fill this in. */
KASSERT(bp->b_rcred == NOCRED, ("leaking read ucred"));
@ -778,11 +767,7 @@ spec_getpages(ap)
spec_xstrategy(bp->b_vp, bp);
s = splbio();
/* We definitely need to be at splbio here. */
while ((bp->b_flags & B_DONE) == 0)
tsleep(bp, PVM, "spread", 0);
bwait(bp, PVM, "spread");
splx(s);
if ((bp->b_ioflags & BIO_ERROR) != 0) {

14
sys/kern/kern_physio.c
View File

@ -30,12 +30,6 @@
#include <vm/vm.h>
#include <vm/vm_extern.h>
static void
physwakeup(struct buf *bp)
{
wakeup(bp);
}
int
physio(dev_t dev, struct uio *uio, int ioflag)
{
@ -68,7 +62,7 @@ physio(dev_t dev, struct uio *uio, int ioflag)
else
bp->b_iocmd = BIO_WRITE;
bp->b_dev = dev;
bp->b_iodone = physwakeup;
bp->b_iodone = bdone;
bp->b_data = uio->uio_iov[i].iov_base;
bp->b_bcount = uio->uio_iov[i].iov_len;
bp->b_offset = uio->uio_offset;
@ -116,8 +110,10 @@ physio(dev_t dev, struct uio *uio, int ioflag)
DEV_STRATEGY(bp);
spl = splbio();
while ((bp->b_flags & B_DONE) == 0)
tsleep(bp, PRIBIO, "physstr", 0);
if (uio->uio_rw == UIO_READ)
bwait(bp, PRIBIO, "physrd");
else
bwait(bp, PRIBIO, "physwr");
splx(spl);
if (uio->uio_segflg == UIO_USERSPACE)

47
sys/kern/vfs_bio.c
View File

@ -212,6 +212,12 @@ static int needsbuffer;
*/
static struct mtx nblock;
/*
* Lock that protects against bwait()/bdone()/B_DONE races.
*/
static struct mtx bdonelock;
/*
* Definitions for the buffer free lists.
*/
@ -484,6 +490,7 @@ bufinit(void)
mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF);
mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF);
mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF);
mtx_init(&bdonelock, "bdone lock", NULL, MTX_DEF);
/* next, make a null set of free lists */
for (i = 0; i < BUFFER_QUEUES; i++)
@ -2925,11 +2932,13 @@ allocbuf(struct buf *bp, int size)
void
biodone(struct bio *bp)
{
mtx_lock(&bdonelock);
bp->bio_flags |= BIO_DONE;
if (bp->bio_done == NULL)
wakeup(bp);
mtx_unlock(&bdonelock);
if (bp->bio_done != NULL)
bp->bio_done(bp);
else
wakeup(bp);
}
/*
@ -2942,8 +2951,10 @@ int
biowait(struct bio *bp, const char *wchan)
{
mtx_lock(&bdonelock);
while ((bp->bio_flags & BIO_DONE) == 0)
msleep(bp, NULL, PRIBIO, wchan, hz / 10);
msleep(bp, &bdonelock, PRIBIO, wchan, hz / 10);
mtx_unlock(&bdonelock);
if (bp->bio_error != 0)
return (bp->bio_error);
if (!(bp->bio_flags & BIO_ERROR))
@ -3002,12 +3013,10 @@ bufwait(register struct buf * bp)
int s;
s = splbio();
while ((bp->b_flags & B_DONE) == 0) {
if (bp->b_iocmd == BIO_READ)
tsleep(bp, PRIBIO, "biord", 0);
else
tsleep(bp, PRIBIO, "biowr", 0);
}
if (bp->b_iocmd == BIO_READ)
bwait(bp, PRIBIO, "biord");
else
bwait(bp, PRIBIO, "biowr");
splx(s);
if (bp->b_flags & B_EINTR) {
bp->b_flags &= ~B_EINTR;
@ -3214,7 +3223,7 @@ bufdone(struct buf *bp)
else
bqrelse(bp);
} else {
wakeup(bp);
bdone(bp);
}
splx(s);
}
@ -3697,6 +3706,24 @@ vunmapbuf(struct buf *bp)
bp->b_data = bp->b_saveaddr;
}
void
bdone(struct buf *bp)
{
mtx_lock(&bdonelock);
bp->b_flags |= B_DONE;
wakeup(bp);
mtx_unlock(&bdonelock);
}
void
bwait(struct buf *bp, u_char pri, const char *wchan)
{
mtx_lock(&bdonelock);
while ((bp->b_flags & B_DONE) == 0)
msleep(bp, &bdonelock, pri, wchan, 0);
mtx_unlock(&bdonelock);
}
#include "opt_ddb.h"
#ifdef DDB
#include <ddb/ddb.h>

2
sys/sys/buf.h
View File

@ -528,6 +528,8 @@ void pbrelvp(struct buf *);
int allocbuf(struct buf *bp, int size);
void reassignbuf(struct buf *, struct vnode *);
struct buf *trypbuf(int *);
void bwait(struct buf *, u_char, const char *);
void bdone(struct buf *);
#endif /* _KERNEL */