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| author | Marcin Wojtas <mw@FreeBSD.org> | 2019-03-01 01:18:39 +0000 |
|---|---|---|
| committer | Marcin Wojtas <mw@FreeBSD.org> | 2019-03-01 01:18:39 +0000 |
| commit | e3431664dff30f3d9a7f324a2a1b88ca0c0d9886 (patch) | |
| tree | 2e5563db7324c9c7c58416a93ca86f14d6c31922 /sys/kern/subr_bus.c | |
| parent | c8e720aaaeb6b1efe836459c30b0e1782ade5c2a (diff) | |
| download | src-e3431664dff30f3d9a7f324a2a1b88ca0c0d9886.tar.gz src-e3431664dff30f3d9a7f324a2a1b88ca0c0d9886.zip | |
Prevent detaching driver if the attach is not finished
When the device is in attaching state, detach should return
EBUSY instead of success. In other case, there could be race
between attach and detach during the driver unloading.
If driver goes sleep and releases GIANT lock during attaching,
unloading module could start. In such case when attach continues
after module unload, page fault "supervisor read instruction,
page not present" occurred.
This patch works around the real issue, which is a locking
deficiency of the busses.
Submitted by: Rafal Kozik <rk@semihalf.com>
Reviewed by: imp
Obtained from: Semihalf
MFC after: 2 weeks
Sponsored by: Amazon, Inc.
Differential Revision: https://reviews.freebsd.org/D19375
Notes
Notes:
svn path=/head/; revision=344676
Diffstat (limited to 'sys/kern/subr_bus.c')
| -rw-r--r-- | sys/kern/subr_bus.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/sys/kern/subr_bus.c b/sys/kern/subr_bus.c index 937cacd21f94..ba177f7895b3 100644 --- a/sys/kern/subr_bus.c +++ b/sys/kern/subr_bus.c @@ -3004,6 +3004,10 @@ device_detach(device_t dev) PDEBUG(("%s", DEVICENAME(dev))); if (dev->state == DS_BUSY) return (EBUSY); + if (dev->state == DS_ATTACHING) { + device_printf(dev, "device in attaching state! Deferring detach.\n"); + return (EBUSY); + } if (dev->state != DS_ATTACHED) return (0); |