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Add a D_NOGIANT flag which can be set in a struct cdevsw to indicate

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that a particular device driver is not Giant-challenged.

SPECFS will DROP_GIANT() ... PICKUP_GIANT() around calls to the
driver in question.

Notice that the interrupt path is not affected by this!

This does _NOT_ work for drivers accessed through cdevsw->d_strategy()
ie drivers for disk(-like), some tapes, maybe others.
This commit is contained in:
phk 2002-09-27 19:47:59 +00:00
parent 3fbb04e11f
commit 5031f247a0
3 changed files with 78 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

89
sys/fs/specfs/spec_vnops.c
View File

@ -198,7 +198,12 @@ spec_open(ap)
vp->v_vflag |= VV_ISTTY;
VOP_UNLOCK(vp, 0, td);
error = (*dsw->d_open)(dev, ap->a_mode, S_IFCHR, td);
if(dsw->d_flags & D_NOGIANT) {
DROP_GIANT();
error = dsw->d_open(dev, ap->a_mode, S_IFCHR, td);
PICKUP_GIANT();
} else
error = dsw->d_open(dev, ap->a_mode, S_IFCHR, td);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
if (error)
@ -254,12 +259,19 @@ spec_read(ap)
uio = ap->a_uio;
td = uio->uio_td;
resid = uio->uio_resid;
struct cdevsw *dsw;
if (resid == 0)
return (0);
dsw = devsw(dev);
VOP_UNLOCK(vp, 0, td);
error = (*devsw(dev)->d_read)(dev, uio, ap->a_ioflag);
if (dsw->d_flags & D_NOGIANT) {
DROP_GIANT();
error = dsw->d_read(dev, uio, ap->a_ioflag);
PICKUP_GIANT();
} else
error = dsw->d_read(dev, uio, ap->a_ioflag);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
if (uio->uio_resid != resid || (error == 0 && resid != 0))
vfs_timestamp(&dev->si_atime);
@ -284,15 +296,22 @@ spec_write(ap)
struct uio *uio;
dev_t dev;
int error, resid;
struct cdevsw *dsw;
vp = ap->a_vp;
dev = vp->v_rdev;
dsw = devsw(dev);
uio = ap->a_uio;
td = uio->uio_td;
resid = uio->uio_resid;
VOP_UNLOCK(vp, 0, td);
error = (*devsw(dev)->d_write) (dev, uio, ap->a_ioflag);
if (dsw->d_flags & D_NOGIANT) {
DROP_GIANT();
error = dsw->d_write(dev, uio, ap->a_ioflag);
PICKUP_GIANT();
} else
error = dsw->d_write(dev, uio, ap->a_ioflag);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
if (uio->uio_resid != resid || (error == 0 && resid != 0)) {
vfs_timestamp(&dev->si_ctime);
@ -318,10 +337,18 @@ spec_ioctl(ap)
{
dev_t dev;
int error;
struct cdevsw *dsw;
dev = ap->a_vp->v_rdev;
error = (*devsw(dev)->d_ioctl)(dev, ap->a_command,
ap->a_data, ap->a_fflag, ap->a_td);
dsw = devsw(dev);
if (dsw->d_flags & D_NOGIANT) {
DROP_GIANT();
error = dsw->d_ioctl(dev, ap->a_command,
ap->a_data, ap->a_fflag, ap->a_td);
PICKUP_GIANT();
} else
error = dsw->d_ioctl(dev, ap->a_command,
ap->a_data, ap->a_fflag, ap->a_td);
if (error == ENOIOCTL)
error = ENOTTY;
return (error);
@ -338,9 +365,18 @@ spec_poll(ap)
} */ *ap;
{
dev_t dev;
struct cdevsw *dsw;
int error;
dev = ap->a_vp->v_rdev;
return (*devsw(dev)->d_poll)(dev, ap->a_events, ap->a_td);
dsw = devsw(dev);
if (dsw->d_flags & D_NOGIANT) {
DROP_GIANT();
error = dsw->d_poll(dev, ap->a_events, ap->a_td);
PICKUP_GIANT();
} else
error = dsw->d_poll(dev, ap->a_events, ap->a_td);
return(error);
}
/* ARGSUSED */
@ -352,11 +388,20 @@ spec_kqfilter(ap)
} */ *ap;
{
dev_t dev;
struct cdevsw *dsw;
int error;
dev = ap->a_vp->v_rdev;
if (devsw(dev)->d_flags & D_KQFILTER)
return (*devsw(dev)->d_kqfilter)(dev, ap->a_kn);
return (1);
dsw = devsw(dev);
if (!(dsw->d_flags & D_KQFILTER))
return (1);
if (dsw->d_flags & D_NOGIANT) {
DROP_GIANT();
error = dsw->d_kqfilter(dev, ap->a_kn);
PICKUP_GIANT();
} else
error = dsw->d_kqfilter(dev, ap->a_kn);
return (error);
}
/*
@ -461,6 +506,7 @@ spec_strategy(ap)
struct vnode *vp;
struct mount *mp;
int error;
struct cdevsw *dsw;
bp = ap->a_bp;
vp = ap->a_vp;
@ -506,10 +552,18 @@ spec_strategy(ap)
biodone(&bp->b_io);
return (0);
}
KASSERT(devsw(bp->b_dev)->d_strategy != NULL,
dsw = devsw(bp->b_dev);
KASSERT(dsw->d_strategy != NULL,
("No strategy on dev %s responsible for buffer %p\n",
devtoname(bp->b_dev), bp));
DEV_STRATEGY(bp, 0);
if (dsw->d_flags & D_NOGIANT) {
DROP_GIANT();
DEV_STRATEGY(bp, 0);
PICKUP_GIANT();
} else
DEV_STRATEGY(bp, 0);
return (0);
}
@ -591,6 +645,8 @@ spec_close(ap)
struct vnode *vp = ap->a_vp, *oldvp;
struct thread *td = ap->a_td;
dev_t dev = vp->v_rdev;
struct cdevsw *dsw;
int error;
/*
* Hack: a tty device that is a controlling terminal
@ -607,6 +663,7 @@ spec_close(ap)
* consideration.
*/
dsw = devsw(dev);
oldvp = NULL;
sx_xlock(&proctree_lock);
if (td && vp == td->td_proc->p_session->s_ttyvp) {
@ -634,14 +691,20 @@ spec_close(ap)
VI_LOCK(vp);
if (vp->v_iflag & VI_XLOCK) {
/* Forced close. */
} else if (devsw(dev)->d_flags & D_TRACKCLOSE) {
} else if (dsw->d_flags & D_TRACKCLOSE) {
/* Keep device updated on status. */
} else if (vcount(vp) > 1) {
VI_UNLOCK(vp);
return (0);
}
VI_UNLOCK(vp);
return (devsw(dev)->d_close(dev, ap->a_fflag, S_IFCHR, td));
if (dsw->d_flags & D_NOGIANT) {
DROP_GIANT();
error = dsw->d_close(dev, ap->a_fflag, S_IFCHR, td);
PICKUP_GIANT();
} else
error = dsw->d_close(dev, ap->a_fflag, S_IFCHR, td);
return (error);
}
/*

1
sys/sys/conf.h
View File

@ -208,6 +208,7 @@ typedef int l_modem_t(struct tty *tp, int flag);
#define D_TRACKCLOSE 0x00080000 /* track all closes */
#define D_MMAP_ANON 0x00100000 /* special treatment in vm_mmap.c */
#define D_KQFILTER 0x00200000 /* has kqfilter entry */
#define D_NOGIANT 0x00400000 /* Doesn't want Giant */
/*
* Character device switch table

1
sys/sys/linedisc.h
View File

@ -208,6 +208,7 @@ typedef int l_modem_t(struct tty *tp, int flag);
#define D_TRACKCLOSE 0x00080000 /* track all closes */
#define D_MMAP_ANON 0x00100000 /* special treatment in vm_mmap.c */
#define D_KQFILTER 0x00200000 /* has kqfilter entry */
#define D_NOGIANT 0x00400000 /* Doesn't want Giant */
/*
* Character device switch table