signal: Define __ARCH_HAS_SA_RESTORER so we know whether to clear sa_restorer

Vaguely based on upstream commit 574c4866e33d 'consolidate kernel-side
struct sigaction declarations'.

flush_signal_handlers() needs to know whether sigaction::sa_restorer
is defined, not whether SA_RESTORER is defined.  Define the
__ARCH_HAS_SA_RESTORER macro to indicate this.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
kernel/signal.c: use __ARCH_HAS_SA_RESTORER instead of SA_RESTORER

commit 522cff142d7d2f9230839c9e1f21a4d8bcc22a4a upstream.

__ARCH_HAS_SA_RESTORER is the preferred conditional for use in 3.9 and
later kernels, per Kees.

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Emese Revfy <re.emese@gmail.com>
Cc: Emese Revfy <re.emese@gmail.com>
Cc: PaX Team <pageexec@freemail.hu>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Cc: Julien Tinnes <jln@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
SUNRPC: Add barriers to ensure read ordering in rpc_wake_up_task_queue_locked

commit 1166fde6a923c30f4351515b6a9a1efc513e7d00 upstream.

We need to be careful when testing task->tk_waitqueue in
rpc_wake_up_task_queue_locked, because it can be changed while we
are holding the queue->lock.
By adding appropriate memory barriers, we can ensure that it is safe to
test task->tk_waitqueue for equality if the RPC_TASK_QUEUED bit is set.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tile: expect new initramfs name from hypervisor file system

commit ff7f3efb9abf986f4ecd8793a9593f7ca4d6431a upstream.

The current Tilera boot infrastructure now provides the initramfs
to Linux as a Tilera-hypervisor file named "initramfs", rather than
"initramfs.cpio.gz", as before.  (This makes it reasonable to use
other compression techniques than gzip on the file without having to
worry about the name causing confusion.)  Adapt to use the new name,
but also fall back to checking for the old name.

Cc'ing to stable so that older kernels will remain compatible with
newer Tilera boot infrastructure.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Bluetooth: Fix not closing SCO sockets in the BT_CONNECT2 state

commit eb20ff9c91ddcb2d55c1849a87d3db85af5e88a9 upstream.

With deferred setup for SCO, it is possible that userspace closes the
socket when it is in the BT_CONNECT2 state, after the Connect Request is
received but before the Accept Synchonous Connection is sent.

If this happens the following crash was observed, when the connection is
terminated:

[  +0.000003] hci_sync_conn_complete_evt: hci0 status 0x10
[  +0.000005] sco_connect_cfm: hcon ffff88003d1bd800 bdaddr 40:98:4e:32:d7:39 status 16
[  +0.000003] sco_conn_del: hcon ffff88003d1bd800 conn ffff88003cc8e300, err 110
[  +0.000015] BUG: unable to handle kernel NULL pointer dereference at 0000000000000199
[  +0.000906] IP: [<ffffffff810620dd>] __lock_acquire+0xed/0xe82
[  +0.000000] PGD 3d21f067 PUD 3d291067 PMD 0
[  +0.000000] Oops: 0002 [#1] SMP
[  +0.000000] Modules linked in: rfcomm bnep btusb bluetooth
[  +0.000000] CPU 0
[  +0.000000] Pid: 1481, comm: kworker/u:2H Not tainted 3.9.0-rc1-25019-gad82cdd #1 Bochs Bochs
[  +0.000000] RIP: 0010:[<ffffffff810620dd>]  [<ffffffff810620dd>] __lock_acquire+0xed/0xe82
[  +0.000000] RSP: 0018:ffff88003c3c19d8  EFLAGS: 00010002
[  +0.000000] RAX: 0000000000000001 RBX: 0000000000000246 RCX: 0000000000000000
[  +0.000000] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88003d1be868
[  +0.000000] RBP: ffff88003c3c1a98 R08: 0000000000000002 R09: 0000000000000000
[  +0.000000] R10: ffff88003d1be868 R11: ffff88003e20b000 R12: 0000000000000002
[  +0.000000] R13: ffff88003aaa8000 R14: 000000000000006e R15: ffff88003d1be850
[  +0.000000] FS:  0000000000000000(0000) GS:ffff88003e200000(0000) knlGS:0000000000000000
[  +0.000000] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[  +0.000000] CR2: 0000000000000199 CR3: 000000003c1cb000 CR4: 00000000000006b0
[  +0.000000] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  +0.000000] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[  +0.000000] Process kworker/u:2H (pid: 1481, threadinfo ffff88003c3c0000, task ffff88003aaa8000)
[  +0.000000] Stack:
[  +0.000000]  ffffffff81b16342 0000000000000000 0000000000000000 ffff88003d1be868
[  +0.000000]  ffffffff00000000 00018c0c7863e367 000000003c3c1a28 ffffffff8101efbd
[  +0.000000]  0000000000000000 ffff88003e3d2400 ffff88003c3c1a38 ffffffff81007c7a
[  +0.000000] Call Trace:
[  +0.000000]  [<ffffffff8101efbd>] ? kvm_clock_read+0x34/0x3b
[  +0.000000]  [<ffffffff81007c7a>] ? paravirt_sched_clock+0x9/0xd
[  +0.000000]  [<ffffffff81007fd4>] ? sched_clock+0x9/0xb
[  +0.000000]  [<ffffffff8104fd7a>] ? sched_clock_local+0x12/0x75
[  +0.000000]  [<ffffffff810632d1>] lock_acquire+0x93/0xb1
[  +0.000000]  [<ffffffffa0022339>] ? spin_lock+0x9/0xb [bluetooth]
[  +0.000000]  [<ffffffff8105f3d8>] ? lock_release_holdtime.part.22+0x4e/0x55
[  +0.000000]  [<ffffffff814f6038>] _raw_spin_lock+0x40/0x74
[  +0.000000]  [<ffffffffa0022339>] ? spin_lock+0x9/0xb [bluetooth]
[  +0.000000]  [<ffffffff814f6936>] ? _raw_spin_unlock+0x23/0x36
[  +0.000000]  [<ffffffffa0022339>] spin_lock+0x9/0xb [bluetooth]
[  +0.000000]  [<ffffffffa00230cc>] sco_conn_del+0x76/0xbb [bluetooth]
[  +0.000000]  [<ffffffffa002391d>] sco_connect_cfm+0x2da/0x2e9 [bluetooth]
[  +0.000000]  [<ffffffffa000862a>] hci_proto_connect_cfm+0x38/0x65 [bluetooth]
[  +0.000000]  [<ffffffffa0008d30>] hci_sync_conn_complete_evt.isra.79+0x11a/0x13e [bluetooth]
[  +0.000000]  [<ffffffffa000cd96>] hci_event_packet+0x153b/0x239d [bluetooth]
[  +0.000000]  [<ffffffff814f68ff>] ? _raw_spin_unlock_irqrestore+0x48/0x5c
[  +0.000000]  [<ffffffffa00025f6>] hci_rx_work+0xf3/0x2e3 [bluetooth]
[  +0.000000]  [<ffffffff8103efed>] process_one_work+0x1dc/0x30b
[  +0.000000]  [<ffffffff8103ef83>] ? process_one_work+0x172/0x30b
[  +0.000000]  [<ffffffff8103e07f>] ? spin_lock_irq+0x9/0xb
[  +0.000000]  [<ffffffff8103fc8d>] worker_thread+0x123/0x1d2
[  +0.000000]  [<ffffffff8103fb6a>] ? manage_workers+0x240/0x240
[  +0.000000]  [<ffffffff81044211>] kthread+0x9d/0xa5
[  +0.000000]  [<ffffffff81044174>] ? __kthread_parkme+0x60/0x60
[  +0.000000]  [<ffffffff814f75bc>] ret_from_fork+0x7c/0xb0
[  +0.000000]  [<ffffffff81044174>] ? __kthread_parkme+0x60/0x60
[  +0.000000] Code: d7 44 89 8d 50 ff ff ff 4c 89 95 58 ff ff ff e8 44 fc ff ff 44 8b 8d 50 ff ff ff 48 85 c0 4c 8b 95 58 ff ff ff 0f 84 7a 04 00 00 <f0> ff 80 98 01 00 00 83 3d 25 41 a7 00 00 45 8b b5 e8 05 00 00
[  +0.000000] RIP  [<ffffffff810620dd>] __lock_acquire+0xed/0xe82
[  +0.000000]  RSP <ffff88003c3c19d8>
[  +0.000000] CR2: 0000000000000199
[  +0.000000] ---[ end trace e73cd3b52352dd34 ]---

Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@openbossa.org>
Tested-by: Frederic Dalleau <frederic.dalleau@intel.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Bluetooth: Add support for Dell[QCA 0cf3:0036]

commit d66629c1325399cf080ba8b2fb086c10e5439cdd upstream.

Add support for the AR9462 chip

T:  Bus=03 Lev=01 Prnt=01 Port=01 Cnt=01 Dev#=  3 Spd=12   MxCh= 0
D:  Ver= 1.10 Cls=e0(wlcon) Sub=01 Prot=01 MxPS=64 #Cfgs=  1
P:  Vendor=0cf3 ProdID=0036 Rev= 0.02
C:* #Ifs= 2 Cfg#= 1 Atr=e0 MxPwr=100mA
A:  FirstIf#= 0 IfCount= 2 Cls=e0(wlcon) Sub=01 Prot=01
I:* If#= 0 Alt= 0 #EPs= 3 Cls=e0(wlcon) Sub=01 Prot=01 Driver=btusb
E:  Ad=81(I) Atr=03(Int.) MxPS=  16 Ivl=1ms
E:  Ad=82(I) Atr=02(Bulk) MxPS=  64 Ivl=0ms
E:  Ad=02(O) Atr=02(Bulk) MxPS=  64 Ivl=0ms
I:* If#= 1 Alt= 0 #EPs= 2 Cls=e0(wlcon) Sub=01 Prot=01 Driver=btusb
E:  Ad=83(I) Atr=01(Isoc) MxPS=   0 Ivl=1ms
E:  Ad=03(O) Atr=01(Isoc) MxPS=   0 Ivl=1ms
I:  If#= 1 Alt= 1 #EPs= 2 Cls=e0(wlcon) Sub=01 Prot=01 Driver=btusb
E:  Ad=83(I) Atr=01(Isoc) MxPS=   9 Ivl=1ms
E:  Ad=03(O) Atr=01(Isoc) MxPS=   9 Ivl=1ms
I:  If#= 1 Alt= 2 #EPs= 2 Cls=e0(wlcon) Sub=01 Prot=01 Driver=btusb
E:  Ad=83(I) Atr=01(Isoc) MxPS=  17 Ivl=1ms
E:  Ad=03(O) Atr=01(Isoc) MxPS=  17 Ivl=1ms
I:  If#= 1 Alt= 3 #EPs= 2 Cls=e0(wlcon) Sub=01 Prot=01 Driver=btusb
E:  Ad=83(I) Atr=01(Isoc) MxPS=  25 Ivl=1ms
E:  Ad=03(O) Atr=01(Isoc) MxPS=  25 Ivl=1ms
I:  If#= 1 Alt= 4 #EPs= 2 Cls=e0(wlcon) Sub=01 Prot=01 Driver=btusb
E:  Ad=83(I) Atr=01(Isoc) MxPS=  33 Ivl=1ms
E:  Ad=03(O) Atr=01(Isoc) MxPS=  33 Ivl=1ms
I:  If#= 1 Alt= 5 #EPs= 2 Cls=e0(wlcon) Sub=01 Prot=01 Driver=btusb
E:  Ad=83(I) Atr=01(Isoc) MxPS=  49 Ivl=1ms
E:  Ad=03(O) Atr=01(Isoc) MxPS=  49 Ivl=1ms

Signed-off-by: Ming Lei <ming.lei@canonical.com>
Cc: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
staging: comedi: s626: fix continuous acquisition

commit e4317ce877a31dbb9d96375391c1c4ad2210d637 upstream.

For the s626 driver, there is a bug in the handling of asynchronous
commands on the AI subdevice when the stop source is `TRIG_NONE`.  The
command should run continuously until cancelled, but the interrupt
handler stops the command running after the first scan.

The command set-up function `s626_ai_cmd()` contains this code:

	switch (cmd->stop_src) {
	case TRIG_COUNT:
		/*  data arrives as one packet */
		devpriv->ai_sample_count = cmd->stop_arg;
		devpriv->ai_continous = 0;
		break;
	case TRIG_NONE:
		/*  continous acquisition */
		devpriv->ai_continous = 1;
		devpriv->ai_sample_count = 0;
		break;
	}

The interrupt handler `s626_irq_handler()` contains this code:

		if (!(devpriv->ai_continous))
			devpriv->ai_sample_count--;
		if (devpriv->ai_sample_count <= 0) {
			devpriv->ai_cmd_running = 0;
			/* ... */
		}

So `devpriv->ai_sample_count` is only decremented for the `TRIG_COUNT`
case, but `devpriv->ai_cmd_running` is set to 0 (and the command
stopped) regardless.

Fix this in `s626_ai_cmd()` by setting `devpriv->ai_sample_count = 1`
for the `TRIG_NONE` case.  The interrupt handler will not decrement it
so it will remain greater than 0 and the check for stopping the
acquisition will fail.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
sysfs: fix race between readdir and lseek

commit 991f76f837bf22c5bb07261cfd86525a0a96650c upstream.

While readdir() is running, lseek() may set filp->f_pos as zero,
then may leave filp->private_data pointing to one sysfs_dirent
object without holding its reference counter, so the sysfs_dirent
object may be used after free in next readdir().

This patch holds inode->i_mutex to avoid the problem since
the lock is always held in readdir path.

Reported-by: Dave Jones <davej@redhat.com>
Tested-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
sysfs: handle failure path correctly for readdir()

commit e5110f411d2ee35bf8d202ccca2e89c633060dca upstream.

In case of 'if (filp->f_pos ==  0 or 1)' of sysfs_readdir(),
the failure from filldir() isn't handled, and the reference counter
of the sysfs_dirent object pointed by filp->private_data will be
released without clearing filp->private_data, so use after free
bug will be triggered later.

This patch returns immeadiately under the situation for fixing the bug,
and it is reasonable to return from readdir() when filldir() fails.

Reported-by: Dave Jones <davej@redhat.com>
Tested-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
can: sja1000: fix define conflict on SH

commit f901b6bc404b67d96eca739857c097e022727b71 upstream.

Thias patch fixes a define conflict between the SH architecture and the sja1000
driver:

    drivers/net/can/sja1000/sja1000.h:59:0: warning:
        "REG_SR" redefined [enabled by default]
    arch/sh/include/asm/ptrace_32.h:25:0: note:
         this is the location of the previous definition

A SJA1000_ prefix is added to the offending sja1000 define only, to make a
minimal patch suited for stable. A later patch will add a SJA1000_ prefix to
all defines in sja1000.h.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ath9k_hw: revert chainmask to user configuration after calibration

commit 74632d11a133b5baf6b9d622dd19d2f944d93d94 upstream.

The commit 'ath9k_hw: fix calibration issues on chainmask that don't
include chain 0' changed the hardware chainmask to the chip chainmask
for the duration of the calibration, but the revert to user
configuration in the reset path runs too early.

That causes some issues with limiting the number of antennas (including
spurious failure in hardware-generated packets).

Fix this by reverting the chainmask after the essential parts of the
calibration that need the workaround, and before NF calibration is run.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Reported-by: Wojciech Dubowik <Wojciech.Dubowik@neratec.com>
Tested-by: Wojciech Dubowik <Wojciech.Dubowik@neratec.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
HID: usbhid: quirk for Realtek Multi-card reader

commit 3d464d9b71ef2f2b40a4bc9dcf06794fd1be9d12 upstream.

This device needs to be added to the quirks list with HID_QUIRK_NO_INIT_REPORTS,
otherwise it causes 10 seconds timeout during report initialization.

This fixes Red Hat bugzilla https://bugzilla.redhat.com/show_bug.cgi?id=806587

Signed-off-by: Josh Boyer <jwboyer@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
rtlwifi: usb: add missing freeing of skbuff

commit 36ef0b473fbf43d5db23eea4616cc1d18cec245f upstream.

Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>
Acked-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
b43: N-PHY: increase initial value of "mind" in RSSI calibration

commit e67dd874e60529dbd2e8232babb1e23479ba2ffa upstream.

We're using "mind" variable to find the VCM that got the best polling
results. For each VCM we calculte "currd" which is compared to the
"mind". For PHY rev3+ "currd" gets values around 14k-40k. Looking for a
value smaller than 40 makes no sense, so increase the initial value.

This fixes a regression introduced in 3.4 by commit:
e0c9a0219a8f542e3946fe972a68aacf8c3f906c
(my BCM4322 performance dropped from 18,4Mb/s to 9,26Mb/s)

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
b43: A fix for DMA transmission sequence errors

commit b251412db99ccd4495ce372fec7daee27bf06923 upstream.

Intermittently, b43 will report "Out of order TX status report on DMA ring".
When this happens, the driver must be reset before communication can resume.
The cause of the problem is believed to be an error in the closed-source
firmware; however, all versions of the firmware are affected.

This change uses the observation that the expected status is always 2 less
than the observed value, and supplies a fake status report to skip one
header/data pair.

Not all devices suffer from this problem, but it can occur several times
per second under heavy load. As each occurence kills the unmodified driver,
this patch makes if possible for the affected devices to function. The patch
logs only the first instance of the reset operation to prevent spamming
the logs.

Tested-by: Chris Vine <chris@cvine.freeserve.co.uk>
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
b43: N-PHY: use more bits for offset in RSSI calibration

commit 2e1253d640eb7f8707d2591c93097c1e9f9c71d5 upstream.

When calculating "offset" for final RSSI calibration we're using numbers
bigger than s8 can hold. We have for example:
offset[j] = 232 - poll_results[j];
formula. If poll_results[j] is small enough (it usually is) we treat
number's bit as a sign bit. For example 232 - 1 becomes:
0xE8 - 0x1 = 0xE7, which is not 231 but -25.

This code was introduced in e0c9a0219a8f542e3946fe972a68aacf8c3f906c
and caused stability regression on some cards, for ex. BCM4322.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
tg3: fix length overflow in VPD firmware parsing

commit 715230a44310a8cf66fbfb5a46f9a62a9b2de424 upstream.

Commit 184b89044fb6e2a74611dafa69b1dce0d98612c6 ("tg3: Use VPD fw version
when present") introduced VPD parsing that contained a potential length
overflow.

Limit the hardware's reported firmware string length (max 255 bytes) to
stay inside the driver's firmware string length (32 bytes). On overflow,
truncate the formatted firmware string instead of potentially overwriting
portions of the tg3 struct.

http://cansecwest.com/slides/2013/PrivateCore%20CSW%202013.pdf

Signed-off-by: Kees Cook <keescook@chromium.org>
Reported-by: Oded Horovitz <oded@privatecore.com>
Reported-by: Brad Spengler <spender@grsecurity.net>
Cc: Matt Carlson <mcarlson@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
iommu/amd: Make sure dma_ops are set for hotplug devices

commit c2a2876e863356b092967ea62bebdb4dd663af80 upstream.

There is a bug introduced with commit 27c2127 that causes
devices which are hot unplugged and then hot-replugged to
not have per-device dma_ops set. This causes these devices
to not function correctly. Fixed with this patch.

Reported-by: Andreas Degert <andreas.degert@googlemail.com>
Signed-off-by: Joerg Roedel <joro@8bytes.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
xen/blkback: correctly respond to unknown, non-native requests

commit 0e367ae46503cfe7791460c8ba8434a5d60b2bd5 upstream.

If the frontend is using a non-native protocol (e.g., a 64-bit
frontend with a 32-bit backend) and it sent an unrecognized request,
the request was not translated and the response would have the
incorrect ID.  This may cause the frontend driver to behave
incorrectly or crash.

Since the ID field in the request is always in the same place,
regardless of the request type we can get the correct ID and make a
valid response (which will report BLKIF_RSP_EOPNOTSUPP).

This bug affected 64-bit SLES 11 guests when using a 32-bit backend.
This guest does a BLKIF_OP_RESERVED_1 (BLKIF_OP_PACKET in the SLES
source) and would crash in blkif_int() as the ID in the response would
be invalid.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
xen-blkback: fix dispatch_rw_block_io() error path

commit 0e5e098ac22dae38f957e951b70d3cf73beff0f7 upstream.

Commit 7708992 ("xen/blkback: Seperate the bio allocation and the bio
submission") consolidated the pendcnt updates to just a single write,
neglecting the fact that the error path relied on it getting set to 1
up front (such that the decrement in __end_block_io_op() would actually
drop the count to zero, triggering the necessary cleanup actions).

Also remove a misleading and a stale (after said commit) comment.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>