Author: kan
Date: Tue Mar 26 01:17:06 2013
New Revision: 248712
URL: http://svnweb.freebsd.org/changeset/base/248712
Log:
Do not pass unmapped buffers to drivers that cannot handle them
In physio, check if device can handle unmapped IO and pass an
appropriately mapped buffer to the driver strategy routine. The
only driver in the tree that can handle unmapped buffers is one
exposed by GEOM, so mark it as such with the new flag in the
driver cdevsw structure.
This fixes insta-panics on hosts, running dconschat, as /dev/fwmem
is an example of the driver that makes use of physio routine, but
bypasses the g_down thread, where the buffer gets mapped normally.
Discussed with: kib (earlier version)
Modified:
head/sys/geom/geom_dev.c
head/sys/kern/kern_physio.c
head/sys/sys/conf.h
Modified: head/sys/geom/geom_dev.c
==============================================================================
--- head/sys/geom/geom_dev.c Mon Mar 25 23:38:01 2013 (r248711)
+++ head/sys/geom/geom_dev.c Tue Mar 26 01:17:06 2013 (r248712)
@@ -78,7 +78,7 @@ static struct cdevsw g_dev_cdevsw = {
.d_ioctl = g_dev_ioctl,
.d_strategy = g_dev_strategy,
.d_name = "g_dev",
- .d_flags = D_DISK | D_TRACKCLOSE,
+ .d_flags = D_DISK | D_TRACKCLOSE | D_UNMAPPED_IO,
};
static g_taste_t g_dev_taste;
Modified: head/sys/kern/kern_physio.c
==============================================================================
--- head/sys/kern/kern_physio.c Mon Mar 25 23:38:01 2013 (r248711)
+++ head/sys/kern/kern_physio.c Tue Mar 26 01:17:06 2013 (r248712)
@@ -91,11 +91,21 @@ physio(struct cdev *dev, struct uio *uio
bp->b_blkno = btodb(bp->b_offset);
- if (uio->uio_segflg == UIO_USERSPACE)
- if (vmapbuf(bp, 0) < 0) {
+ if (uio->uio_segflg == UIO_USERSPACE) {
+ struct cdevsw *csw;
+ int mapped;
+
+ csw = dev->si_devsw;
+ if (csw != NULL &&
+ (csw->d_flags & D_UNMAPPED_IO) != 0)
+ mapped = 0;
+ else
+ mapped = 1;
+ if (vmapbuf(bp, mapped) < 0) {
error = EFAULT;
goto doerror;
}
+ }
dev_strategy(dev, bp);
if (uio->uio_rw == UIO_READ)
Modified: head/sys/sys/conf.h
==============================================================================
--- head/sys/sys/conf.h Mon Mar 25 23:38:01 2013 (r248711)
+++ head/sys/sys/conf.h Tue Mar 26 01:17:06 2013 (r248712)
@@ -167,6 +167,7 @@ typedef int dumper_t(
#define D_MMAP_ANON 0x00100000 /* special treatment in
vm_mmap.c */
#define D_NEEDGIANT 0x00400000 /* driver want Giant */
#define D_NEEDMINOR 0x00800000 /* driver uses clone_create() */
+#define D_UNMAPPED_IO 0x01000000 /* d_strategy can accept
unmapped IO */
/*
* Version numbers.
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