With scsi-mq enabled, userspace programs can get unexpected EWOULDBLOCK
(a.k.a. EAGAIN) errors when submitting commands to the SCSI generic
driver.  Fix by calling blk_get_request() with GFP_KERNEL instead of
GFP_ATOMIC.

Note: to avoid introducing a potential deadlock, this patch should be
applied after the patch titled "sg: fix unkillable I/O wait deadlock
with scsi-mq".

Cc: <stable@vger.kernel.org> # 3.17+
Signed-off-by: NTony Battersby <tonyb@cybernetics.com>
Acked-by: NDouglas Gilbert <dgilbert@interlog.com>
Tested-by: NDouglas Gilbert <dgilbert@interlog.com>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

When using the write()/read() interface for submitting commands, the
SCSI generic driver does not call blk_put_request() on a completed SCSI
command until userspace calls read() to get the command completion.
Since scsi-mq uses a fixed number of preallocated requests, this makes
it possible for userspace to exhaust the entire preallocated supply of
requests.  For places in the kernel that call blk_get_request() with
GFP_KERNEL, this can cause the calling process to deadlock in a
permanent unkillable I/O wait in blk_get_request() -> ... -> bt_get().
For places in the kernel that call blk_get_request() with GFP_ATOMIC,
this can cause blk_get_request() always to return -EWOULDBLOCK.  Note
that these problems happen only if scsi-mq is enabled.  Prevent the
problems by calling blk_put_request() as soon as the SCSI command
completes instead of waiting for userspace to call read().

Cc: <stable@vger.kernel.org> # 3.17+
Signed-off-by: NTony Battersby <tonyb@cybernetics.com>
Acked-by: NDouglas Gilbert <dgilbert@interlog.com>
Tested-by: NDouglas Gilbert <dgilbert@interlog.com>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

Fix SCSI generic read() incorrectly returning success after detecting an
error.

Cc: <stable@vger.kernel.org>
Signed-off-by: NTony Battersby <tonyb@cybernetics.com>
Acked-by: NDouglas Gilbert <dgilbert@interlog.com>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

Make use of a new interface provided by iov_iter, backed by
scatter-gather list of iovec, instead of the old interface based on
sg_iovec. Also use iov_iter_advance() instead of manual iteration.

This commit should contain only literal replacements, without
functional changes.

Cc: Christoph Hellwig <hch@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Doug Gilbert <dgilbert@interlog.com>
Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
Signed-off-by: NKent Overstreet <kmo@daterainc.com>
[dpark: add more description in commit message]
Signed-off-by: NDongsu Park <dongsu.park@profitbricks.com>
[hch: fixed to do a deep clone of the iov_iter, and to properly use
      the iov_iter direction]
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NMing Lei <tom.leiming@gmail.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

The 'data_dir' variable is not used in sg_common_write(), hence
remove this variable.
Signed-off-by: NBart Van Assche <bart.vanassche@sandisk.com>
Acked-by: NDouglas Gilbert <dgilbert@interlog.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

The calling conventions for this function are bad as it could return
-ENODEV both for a device not currently online and a not recognized ioctl.

Add a new scsi_ioctl_block_when_processing_errors function that wraps
scsi_block_when_processing_errors with the a special case for the
SG_SCSI_RESET ioctl command, and handle the SG_SCSI_RESET case itself
in scsi_ioctl.  All callers of scsi_ioctl now must call the above helper
to check for the EH state, so that the ioctl handler itself doesn't
have to.
Reported-by: NRobert Elliott <Elliott@hp.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: NHannes Reinecke <hare@suse.de>

Pull the common code from the two callers into the function,
and rename it to scsi_ioctl_reset.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: NHannes Reinecke <hare@suse.de>

We should be using the standard dev_printk() variants for
sense code printing.

[hch: remove __scsi_print_sense call in xen-scsiback, Acked by Juergen]
[hch: folded bracing fix from Dan Carpenter]
Signed-off-by: NHannes Reinecke <hare@suse.de>
Reviewed-by: NRobert Elliott <elliott@hp.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Like scmd_printk(), but the device name is passed in as
a string. Can be used by eg ULDs which do not have access
to the scsi_cmnd structure.
Signed-off-by: NHannes Reinecke <hare@suse.de>
Reviewed-by: NRobert Elliott <elliott@hp.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

Further to a January 2013 thread titled: "[PATCH] SG_SCSI_RESET ioctl
should only perform requested operation" by Jeremy Linton a patch (v3)
is presented that expands the existing ioctl to include "no_escalate"
versions to the existing resets. This requires no changes to SCSI low
level drivers (LLDs); it adds several more finely tuned reset options
to the user space. For example:

   /* This call remains the same, with the same escalating semantics
    * if the device (LU) reset fail. That is: on failure to try a
    * target reset and if that fails, try a bus reset, and if that fails
    * try a host (i.e. LLD) reset. */
   val = SG_SCSI_RESET_DEVICE;
   res = ioctl(<sg_or_block_fd>, SG_SCSI_RESET, &val);

   /* What follows is a new option introduced by this patch series. Only
    * a device reset is attempted. If that fails then an appropriate
    * error code is provided. N.B. There is no reset escalation. */
   val = SG_SCSI_RESET_DEVICE | SG_SCSI_RESET_NO_ESCALATE;
   res = ioctl(<sg_or_block_fd>, SG_SCSI_RESET, &val);
Signed-off-by: NDouglas Gilbert <dgilbert@interlog.com>
Reviewed-by: NJeremy Linton <jlinton@tributary.com>
Reviewed-by: NHannes Reinecke <hare@suse.de>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

The blk_get_request function may fail in low-memory conditions or during
device removal (even if __GFP_WAIT is set). To distinguish between these
errors, modify the blk_get_request call stack to return the appropriate
ERR_PTR. Verify that all callers check the return status and consider
IS_ERR instead of a simple NULL pointer check.

For consistency, make a similar change to the blk_mq_alloc_request leg
of blk_get_request.  It may fail if the queue is dead, or the caller was
unwilling to wait.
Signed-off-by: NJoe Lawrence <joe.lawrence@stratus.com>
Acked-by: Jiri Kosina <jkosina@suse.cz> [for pktdvd]
Acked-by: Boaz Harrosh <bharrosh@panasas.com> [for osd]
Reviewed-by: NJeff Moyer <jmoyer@redhat.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

Avoid taking the queue_lock to check the per-device queue limit.  Instead
we do an atomic_inc_return early on to grab our slot in the queue,
and if necessary decrement it after finishing all checks.

Unlike the host and target busy counters this doesn't allow us to avoid the
queue_lock in the request_fn due to the way the interface works, but it'll
allow us to prepare for using the blk-mq code, which doesn't use the
queue_lock at all, and it at least avoids a queue_lock round trip in
scsi_device_unbusy, which is still important given how busy the queue_lock
is.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinecke <hare@suse.de>
Reviewed-by: NWebb Scales <webbnh@hp.com>
Acked-by: NJens Axboe <axboe@kernel.dk>
Tested-by: NBart Van Assche <bvanassche@acm.org>
Tested-by: NRobert Elliott <elliott@hp.com>

Update the sg driver to use dev_printk() variants instead of
plain printk(); this will prefix logging messages with the
appropriate device.
Signed-off-by: NHannes Reinecke <hare@suse.de>
Acked-by: NDoug Gilbert <dgilbert@interlog.com>
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

The SCSI standard defines 64-bit values for LUNs, and large arrays
employing large or hierarchical LUN numbers become more and more
common.

So update the linux SCSI stack to use 64-bit LUN numbers.
Signed-off-by: NHannes Reinecke <hare@suse.de>
Reviewed-by: NChristoph Hellwig <hch@infradead.org>
Reviewed-by: NEwan Milne <emilne@redhat.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

This addresses a problem reported by Vaughan Cao concerning
the correctness of the O_EXCL logic in the sg driver. POSIX
doesn't defined O_EXCL semantics on devices but "allow only
one open file descriptor at a time per sg device" is a rough
definition. The sg driver's semantics have been to wait
on an open() when O_NONBLOCK is not given and there are
O_EXCL headwinds. Nasty things can happen during that wait
such as the device being detached (removed). So multiple
locks are reworked in this patch making it large and hard
to break down into digestible bits.

This patch is against Linus's current git repository which
doesn't include any sg patches sent in the last few weeks.
Hence this patch touches as little as possible that it
doesn't need to and strips out most SCSI_LOG_TIMEOUT()
changes in v3 because Hannes said he was going to rework all
that stuff.

The sg3_utils package has several test programs written to
test this patch. See examples/sg_tst_excl*.cpp .

Not all the locks and flags in sg have been re-worked in
this patch, notably sg_request::done . That can wait for
a follow-up patch if this one meets with approval.
Signed-off-by: NDouglas Gilbert <dgilbert@interlog.com>
Reviewed-by: NHannes Reinecke <hare@suse.de>

When the SG_IO ioctl was copied into the block layer and
later into the bsg driver, subtle differences emerged.

One difference is the way injected commands are queued through
the block layer (i.e. this is not SCSI device queueing nor SATA
NCQ). Summarizing:
   - SG_IO in the block layer: blk_exec*(at_head=false)
   - sg SG_IO: at_head=true
   - bsg SG_IO: at_head=true

Some time ago Boaz Harrosh introduced a sg v4 flag called
BSG_FLAG_Q_AT_TAIL to override the bsg driver default.
This patch does the equivalent for the sg driver.

ChangeLog:
     Introduce SG_FLAG_Q_AT_TAIL flag to cause commands
     to be injected into the block layer with
     at_head=false.
Signed-off-by: NDouglas Gilbert <dgilbert@interlog.com>
Reviewed-by: NMike Christie <michaelc@cs.wisc.edu>
Reviewed-by: NEwan D. Milne <emilne@redhat.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

 - remove the 16 byte CDB (SCSI command) length limit from the sg driver
   by handling longer CDBs the same way as the bsg driver. Remove comment
   from sg.h public interface about the cmd_len field being limited to 16
   bytes.
 - remove some dead code caused by this change
 - cleanup comment block at the top of sg.h, fix urls
Signed-off-by: NDouglas Gilbert <dgilbert@interlog.com>
Reviewed-by: NMike Christie <michaelc@cs.wisc.edu>
Reviewed-by: NHannes Reinecke <hare@suse.de>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

This prevents integer overflow when converting the request queue's
max_sectors from sectors to bytes.  However, this is a preparation for
extending the data type of max_sectors in struct Scsi_Host and
scsi_host_template.  So, it is impossible to happen this integer
overflow for now, because SCSI low-level drivers can not specify
max_sectors greater than 0xffff due to the data type limitation.
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Acked by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

With the optimizations around not clearing the full request at alloc
time, we are leaving some of the needed init for REQ_TYPE_BLOCK_PC
up to the user allocating the request.

Add a blk_rq_set_block_pc() that sets the command type to
REQ_TYPE_BLOCK_PC, and properly initializes the members associated
with this type of request. Update callers to use this function instead
of manipulating rq->cmd_type directly.

Includes fixes from Christoph Hellwig <hch@lst.de> for my half-assed
attempt.
Signed-off-by: NJens Axboe <axboe@fb.com>

This reverts commit 15b06f9a.

This is one of four patches that was causing this bug

[  205.372823] ================================================
[  205.372901] [ BUG: lock held when returning to user space! ]
[  205.372979] 3.12.0-rc6-hw-debug-pagealloc+ #67 Not tainted
[  205.373055] ------------------------------------------------
[  205.373132] megarc.bin/5283 is leaving the kernel with locks still held!
[  205.373212] 1 lock held by megarc.bin/5283:
[  205.373285]  #0:  (&sdp->o_sem){.+.+..}, at: [<ffffffff8161e650>] sg_open+0x3a0/0x4d0

Cc: Vaughan Cao <vaughan.cao@oracle.com>
Acked-by: NDouglas Gilbert <dgilbert@interlog.com>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

This reverts commit 00b2d9d6.

This is one of four patches that was causing this bug

[  205.372823] ================================================
[  205.372901] [ BUG: lock held when returning to user space! ]
[  205.372979] 3.12.0-rc6-hw-debug-pagealloc+ #67 Not tainted
[  205.373055] ------------------------------------------------
[  205.373132] megarc.bin/5283 is leaving the kernel with locks still held!
[  205.373212] 1 lock held by megarc.bin/5283:
[  205.373285]  #0:  (&sdp->o_sem){.+.+..}, at: [<ffffffff8161e650>] sg_open+0x3a0/0x4d0

Cc: Vaughan Cao <vaughan.cao@oracle.com>
Acked-by: NDouglas Gilbert <dgilbert@interlog.com>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

This reverts commit e32c9e63.

This is one of four patches that was causing this bug

[  205.372823] ================================================
[  205.372901] [ BUG: lock held when returning to user space! ]
[  205.372979] 3.12.0-rc6-hw-debug-pagealloc+ #67 Not tainted
[  205.373055] ------------------------------------------------
[  205.373132] megarc.bin/5283 is leaving the kernel with locks still held!
[  205.373212] 1 lock held by megarc.bin/5283:
[  205.373285]  #0:  (&sdp->o_sem){.+.+..}, at: [<ffffffff8161e650>] sg_open+0x3a0/0x4d0

Cc: Vaughan Cao <vaughan.cao@oracle.com>
Acked-by: NDouglas Gilbert <dgilbert@interlog.com>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

This reverts commit 1f962ebc.

This is one of four patches that was causing this bug

[  205.372823] ================================================
[  205.372901] [ BUG: lock held when returning to user space! ]
[  205.372979] 3.12.0-rc6-hw-debug-pagealloc+ #67 Not tainted
[  205.373055] ------------------------------------------------
[  205.373132] megarc.bin/5283 is leaving the kernel with locks still held!
[  205.373212] 1 lock held by megarc.bin/5283:
[  205.373285]  #0:  (&sdp->o_sem){.+.+..}, at: [<ffffffff8161e650>] sg_open+0x3a0/0x4d0

Cc: Vaughan Cao <vaughan.cao@oracle.com>
Acked-by: NDouglas Gilbert <dgilbert@interlog.com>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

Push file descriptor list locking down to per-device locking. Let sg_index_lock
only protect device lookup.
sdp->detached is also set and checked with this lock held.
Signed-off-by: NVaughan Cao <vaughan.cao@oracle.com>
Acked-by: NDouglas Gilbert <dgilbert@interlog.com>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

@Detached is set under the protection of sg_index_lock. Without getting the
lock, new sfp will be added during sg removal and there is no chance for it
to be picked out. So check with sg_index_lock held in sg_add_sfp().
Signed-off-by: NVaughan Cao <vaughan.cao@oracle.com>
Acked-by: NDouglas Gilbert <dgilbert@interlog.com>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

Open exclusive check is protected by o_sem, no need sg_open_exclusive_lock.
@exclude is used to record which type of rwsem we are holding.
Signed-off-by: NVaughan Cao <vaughan.cao@oracle.com>
Acked-by: NDouglas Gilbert <dgilbert@interlog.com>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

A race condition may happen if two threads are both trying to open the same sg
with O_EXCL simultaneously. It's possible that they both find fsds list is
empty and get_exclude(sdp) returns 0, then they both call set_exclude() and
break out from wait_event_interruptible and resume open.

Now use rwsem to protect this process. Exclusive open gets write lock and
others get read lock. The lock will be held until file descriptor is closed.
This also leads 'exclude' only a status rather than a check mark.
Signed-off-by: NVaughan Cao <vaughan.cao@oracle.com>
Acked-by: NDouglas Gilbert <dgilbert@interlog.com>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

Faster kernel compiles by way of fewer unnecessary includes.

[akpm@linux-foundation.org: fix fallout]
[akpm@linux-foundation.org: fix build]
Signed-off-by: NKent Overstreet <koverstreet@google.com>
Cc: Zach Brown <zab@redhat.com>
Cc: Felipe Balbi <balbi@ti.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Asai Thambi S P <asamymuthupa@micron.com>
Cc: Selvan Mani <smani@micron.com>
Cc: Sam Bradshaw <sbradshaw@micron.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Reviewed-by: N"Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Convert to the much saner new idr interface.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

A long time ago, in v2.4, VM_RESERVED kept swapout process off VMA,
currently it lost original meaning but still has some effects:

 | effect                 | alternative flags
-+------------------------+---------------------------------------------
1| account as reserved_vm | VM_IO
2| skip in core dump      | VM_IO, VM_DONTDUMP
3| do not merge or expand | VM_IO, VM_DONTEXPAND, VM_HUGETLB, VM_PFNMAP
4| do not mlock           | VM_IO, VM_DONTEXPAND, VM_HUGETLB, VM_PFNMAP

This patch removes reserved_vm counter from mm_struct.  Seems like nobody
cares about it, it does not exported into userspace directly, it only
reduces total_vm showed in proc.

Thus VM_RESERVED can be replaced with VM_IO or pair VM_DONTEXPAND | VM_DONTDUMP.

remap_pfn_range() and io_remap_pfn_range() set VM_IO|VM_DONTEXPAND|VM_DONTDUMP.
remap_vmalloc_range() set VM_DONTEXPAND | VM_DONTDUMP.

[akpm@linux-foundation.org: drivers/vfio/pci/vfio_pci.c fixup]
Signed-off-by: NKonstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Carsten Otte <cotte@de.ibm.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Eric Paris <eparis@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Morris <james.l.morris@oracle.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Kentaro Takeda <takedakn@nttdata.co.jp>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Venkatesh Pallipadi <venki@google.com>
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NJoern Engel <joern@logfs.org>
Acked-by: NDouglas Gilbert <dgilbert@interlog.com>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

With the exception of the detached field, sg_mutex no longer adds any
locking.  detached handling has been broken before and is still broken
and this patch does not seem to make things worse than they were to
begin with.

However, I have observed cases of tasks being blocked for >200s waiting
for sg_mutex.  So the removal clearly adds value for very little cost.
Signed-off-by: NJoern Engel <joern@logfs.org>
Acked-by: NDouglas Gilbert <dgilbert@interlog.com>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

sfds is protected by sg_index_lock - except for sg_open(), where it
isn't.  Change that and add some documentation.
Signed-off-by: NJoern Engel <joern@logfs.org>
Acked-by: NDouglas Gilbert <dgilbert@interlog.com>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

Changes since v1: set_exclude now returns the new value, which gets
rid of the comma expression and the operator precedence bug.  Thanks
to Douglas for spotting it.

sdp->exclude was previously protected by the BKL.  The sg_mutex, which
replaced the BKL, only semi-protected it, as it was missing from
sg_release() and sg_proc_seq_show_debug().  Take an explicit spinlock
for it.
Signed-off-by: NJoern Engel <joern@logfs.org>
Acked-by: NDouglas Gilbert <dgilbert@interlog.com>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

srp->done is protected by sfp->rq_list_lock everywhere, except for this
one case.  Result can be that the wake-up happens before the cacheline
with the changed srp->done has arrived, so the waiter can go back to
sleep and never be woken up again.

The wait_event_interruptible() means that anyone trying to debug this
unlikely race will likely notice everything working fine again, as the
next signal will unwedge things.  Evil.
Signed-off-by: NJoern Engel <joern@logfs.org>
Acked-by: NDouglas Gilbert <dgilbert@interlog.com>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

After sg_release() has been called, noone should be able to actually use
that filedescriptor anymore.  So if closed ever made a difference in the
past five years or so, it would have meant a bug.  Remove it.
Signed-off-by: NJoern Engel <joern@logfs.org>
Acked-by: NDouglas Gilbert <dgilbert@interlog.com>
[jejb: fix up checkpatch warnings]
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

Afaics the use of __wait_event_interruptible() as opposed to
wait_event_interruptible() is purely historic.  So let's follow the rest
of the kernel and check the condition before prepare_to_wait() - and
also make the code a bit nicer.
Signed-off-by: NJoern Engel <joern@logfs.org>
Acked-by: NDouglas Gilbert <dgilbert@interlog.com>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

The while (1) construct isn't actually a loop at all.  So let's not
pretent and obfuscate the code.
Signed-off-by: NJoern Engel <joern@logfs.org>
Acked-by: NDouglas Gilbert <dgilbert@interlog.com>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

blocking is de-facto a constant and the now-removed comment wasn't all
that useful either.  Without them and the resulting indentation the code
is a bit nicer to read.
Signed-off-by: NJoern Engel <joern@logfs.org>
Acked-by: NDouglas Gilbert <dgilbert@interlog.com>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>

Instead of open coding this function use kstrtoul_from_user() directly.
Signed-off-by: NStephen Boyd <sboyd@codeaurora.org>
Acked-by: NDouglas Gilbert <dgilbert@interlog.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NJames Bottomley <JBottomley@Parallels.com>