linux-stable.git/drivers/block/floppy.c, branch v3.6.7

floppy: properly handle failure on add_disk loop

2012-11-05T08:56:49+00:00

commit d60e7ec18c3fb2cbf90969ccd42889eb2d03aef9 upstream.

On floppy initialization, if something failed inside the loop we call
add_disk, there was no cleanup of previous iterations in the error
handling.

Signed-off-by: Herton Ronaldo Krzesinski 
Signed-off-by: Jiri Kosina 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

floppy: do put_disk on current dr if blk_init_queue fails

2012-11-05T08:56:49+00:00

commit 238ab78469c6ab7845b43d5061cd3c92331b2452 upstream.

If blk_init_queue fails, we do not call put_disk on the current dr
(dr is decremented first in the error handling loop).

Reviewed-by: Ben Hutchings 
Signed-off-by: Herton Ronaldo Krzesinski 
Signed-off-by: Jiri Kosina 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

floppy: don't call alloc_ordered_workqueue inside the alloc_disk loop

2012-11-05T08:56:49+00:00

commit b54e1f88897bcacc2cd359f48ea3b39eaf55f084 upstream.

Since commit 070ad7e ("floppy: convert to delayed work and single-thread
wq"), we end up calling alloc_ordered_workqueue multiple times inside
the loop, which shouldn't be intended. Besides the leak, other side
effect in the current code is if blk_init_queue fails, we would end up
calling unregister_blkdev even if we didn't call yet register_blkdev.

Just moved the allocation of floppy_wq before the loop, and adjusted the
code accordingly.

Acked-by: Vivek Goyal 
Reviewed-by: Ben Hutchings 
Signed-off-by: Herton Ronaldo Krzesinski 
Signed-off-by: Jiri Kosina 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

Merge branch 'upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/floppy into for-3.6/drivers

2012-07-31T09:47:36+00:00

floppy: remove duplicated flag FD_RAW_NEED_DISK

2012-07-31T09:38:39+00:00

Fix coccinelle warning (without behavior change):

drivers/block/floppy.c:2518:32-48: duplicated argument to & or |

Signed-off-by: Fengguang Wu 
Signed-off-by: Jiri Kosina

Merge branch 'for-jens' of git://git.drbd.org/linux-drbd into for-3.6/drivers

2012-07-30T07:03:10+00:00

floppy: Run floppy initialization asynchronous

2012-07-04T12:01:40+00:00

floppy_init is quite slow, 3s on my test system to determine
that there is no floppy. Run it asynchronous to the other
init calls to improve boot time.

[jkosina@suse.cz: fix modular build]

Signed-off-by: Andi Kleen 
Signed-off-by: Jiri Kosina

floppy: cancel any pending fd_timeouts before adding a new one

2012-07-03T22:51:22+00:00

In commit 070ad7e793dc ("floppy: convert to delayed work and
single-thread wq") the 'fd_timeout' timer was converted to a delayed
work.  However, the "del_timer(&fd_timeout)" was lost in the process,
and any previous pending timeouts would stay active when we then
re-queued the timeout.

This resulted in the floppy probe sequence having a (stale) 20s timeout
rather than the intended 3s timeout, and thus made booting with the
floppy driver (but no actual floppy controller) take much longer than it
should.

Of course, there's little reason for most people to compile the floppy
driver into the kernel at all, which is why most people never noticed.

Canceling the delayed work where we used to do the del_timer() fixes the
issue, and makes the floppy probing use the proper new timeout instead.
The three second timeout is still very wasteful, but better than the 20s
one.

Reported-and-tested-by: Andi Kleen 
Reported-and-tested-by: Calvin Walton 
Cc: Jiri Kosina 
Signed-off-by: Linus Torvalds

floppy: remove floppy-specific O_EXCL handling

2012-05-18T13:19:11+00:00

Block layer now handles O_EXCL in a generic way for block devices.

The semantics is however different for floppy and all other block devices,
as floppy driver contains its own O_EXCL handling.

The semantics for all-but-floppy bdevs is "there can be at most one O_EXCL
open of this file", while for floppy bdev the semantics is "if someone has
the bdev open with O_EXCL, noone else can open it".

There is actual userspace-observable change in behavior because of this
since commit e525fd89d380c ("block: make blkdev_get/put() handle exclusive
access") -- on kernels containing this commit, mount of /dev/fd0 causes
the fd0 block device be claimed with _EXCL, preventing subsequent
open(/dev/fd0).

Bring things back into shape, i.e.  make it possible, analogically to
other block devices, to mount the floppy and open() it afterwards --
remove the floppy-specific handling and let the generic bdev code O_EXCL
handling take over.

Signed-off-by: Jiri Kosina 
Acked-by: Tejun Heo 
Acked-by: NeilBrown 
Signed-off-by: Andrew Morton 
Signed-off-by: Jiri Kosina

floppy: convert to delayed work and single-thread wq

2012-05-18T13:19:10+00:00

There are several races in floppy driver between bottom half
(scheduled_work) and timers (fd_timeout, fd_timer). Due to slowness
of the actual floppy devices, those races are never (at least to my
knowledge) triggered on a bare floppy metal. However on virtualized
(emulated) floppy drives, which are of course magnitudes faster
than the real ones, these races trigger reliably. They usually exhibit
themselves as NULL pointer dereferences during DMA setup, such as

	BUG: unable to handle kernel NULL pointer dereference at 0000000a
	[ ... snip ... ]
	EIP: 0060:[] EFLAGS: 00010293 CPU: 0
	EAX: ffffe000 EBX: 0000000a ECX: 00000000 EDX: 0000000a
	ESI: c05d2718 EDI: 00000000 EBP: 00000000 ESP: f540fe44
	 DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068
	Process swapper (pid: 0, ti=f540e000 task=c082d5a0 task.ti=c0826000)
	Stack:
	 ffffe000 00001ffc 00000000 00000000 00000000 c05d2718 c0708b40 f540fe80
	 c020470f c05d2718 c0708b40 00000000 f540fe80 0000000a f540fee4 00000000
	 c0708b40 f540fee4 00000000 00000000 c020526b 00000000 c05d2718 c0708b40
	Call Trace:
	 [] dump_trace+0xaf/0x110
	 [] show_trace_log_lvl+0x4b/0x60
	 [] show_trace+0x18/0x20
	 [] dump_stack+0x6d/0x72
	 [] warn_slowpath_common+0x77/0xb0
	 [] warn_slowpath_fmt+0x33/0x40
	 [] setup_DMA+0x14c/0x210 [floppy]
	 [] setup_rw_floppy+0x105/0x190 [floppy]
	 [] run_timer_softirq+0x168/0x2a0
	 [] __do_softirq+0xc2/0x1c0
	 [] do_softirq+0x7d/0xb0
	 [] 0xf54d89ff

but other instances can be easily seen as well. This can be observed at least under
VMWare, VirtualBox and KVM.

This patch converts all the timers and bottom halfs to be processed in a single
workqueue. This aproach has been already discussed back in 2010 if I remember
correctly, and Acked by Linus [1], but it then never made it to the tree.

This all is based on original idea and code of Stephen Hemminger.  I have
ported original Stepen's code to the current state of the floppy driver, and
performed quite some testing (on real hardware), which didn't reveal any issues
(this includes not only writing and reading data, but also formatting
(unfortunately I didn't find any Double-Density disks any more)). Ability to
handle errors properly (supplying known bad floppies) has also been verified.

[1] http://kerneltrap.org/mailarchive/linux-kernel/2010/6/11/4582092

Based-on-patch-by: Stephen Hemminger 
Acked-by: Linus Torvalds 
Signed-off-by: Jiri Kosina