1. 28 Apr, 2016 25 commits
  2. 27 Apr, 2016 9 commits
    • Linus Torvalds's avatar
      Merge branch 'for-4.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq · b75a2bf8
      Linus Torvalds authored
      Pull workqueue fix from Tejun Heo:
       "So, it turns out we had a silly bug in the most fundamental part of
        workqueue for a very long time.  AFAICS, this dates back to pre-git
        era and has quite likely been there from the time workqueue was first
        introduced.
      
        A work item uses its PENDING bit to synchronize multiple queuers.
        Anyone who wins the PENDING bit owns the pending state of the work
        item.  Whether a queuer wins or loses the race, one thing should be
        guaranteed - there will soon be at least one execution of the work
        item - where "after" means that the execution instance would be able
        to see all the changes that the queuer has made prior to the queueing
        attempt.
      
        Unfortunately, we were missing a smp_mb() after clearing PENDING for
        execution, so nothing guaranteed visibility of the changes that a
        queueing loser has made, which manifested as a reproducible blk-mq
        stall.
      
        Lots of kudos to Roman for debugging the problem.  The patch for
        -stable is the minimal one.  For v3.7, Peter is working on a patch to
        make the code path slightly more efficient and less fragile"
      
      * 'for-4.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
        workqueue: fix ghost PENDING flag while doing MQ IO
      b75a2bf8
    • Linus Torvalds's avatar
      Merge branch 'for-4.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup · 763cfc86
      Linus Torvalds authored
      Pull cgroup fixes from Tejun Heo:
       "Two patches to fix a deadlock which can be easily triggered if memcg
        charge moving is used.
      
        This bug was introduced while converting threadgroup locking to a
        global percpu_rwsem and is caused by cgroup controller task migration
        path depending on the ability to create new kthreads.  cpuset had a
        similar issue which was fixed by performing heavy-lifting operations
        asynchronous to task migration.  The two patches fix the same issue in
        memcg in a similar way.  The first patch makes the mechanism generic
        and the second relocates memcg charge moving outside the migration
        path.
      
        Given that we don't want to perform heavy operations while
        writelocking threadgroup lock anyway, moving them out of the way is a
        desirable solution.  One thing to note is that the problem was
        difficult to debug because lockdep couldn't figure out the deadlock
        condition.  Looking into how to improve that"
      
      * 'for-4.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
        memcg: relocate charge moving from ->attach to ->post_attach
        cgroup, cpuset: replace cpuset_post_attach_flush() with cgroup_subsys->post_attach callback
      763cfc86
    • Linus Torvalds's avatar
      Merge branch 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux · 3118e5f9
      Linus Torvalds authored
      Pull i2c fixes from Wolfram Sang:
       "I2C has one buildfix, one ABBA deadlock fix, and three simple 'add ID'
        patches"
      
      * 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
        i2c: exynos5: Fix possible ABBA deadlock by keeping I2C clock prepared
        i2c: cpm: Fix build break due to incompatible pointer types
        i2c: ismt: Add Intel DNV PCI ID
        i2c: xlp9xx: add support for Broadcom Vulcan
        i2c: rk3x: add support for rk3228
      3118e5f9
    • Linus Torvalds's avatar
      Merge tag 'arc-4.6-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc · 24131a61
      Linus Torvalds authored
      Pull ARC fixes from Vineet Gupta:
      
       - lockdep now works for ARCv2 builds
      
       - enable DT reserved-memory binding (for forthcoming HDMI driver)
      
      * tag 'arc-4.6-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc:
        ARC: add support for reserved memory defined by device tree
        ARC: support generic per-device coherent dma mem
        Documentation: dt: arc: fix spelling mistakes
        ARCv2: Enable LOCKDEP
      24131a61
    • Linus Torvalds's avatar
      Merge tag 'nios2-v4.6-fix' of git://git.kernel.org/pub/scm/linux/kernel/git/lftan/nios2 · 508fea71
      Linus Torvalds authored
      Pull arch/nios2 fix from Ley Foon Tan:
       "memset: use the right constraint modifier for the %4 output operand"
      
      * tag 'nios2-v4.6-fix' of git://git.kernel.org/pub/scm/linux/kernel/git/lftan/nios2:
        nios2: memset: use the right constraint modifier for the %4 output operand
      508fea71
    • Linus Torvalds's avatar
      Merge tag 'platform-drivers-x86-v4.6-3' of... · 9453203b
      Linus Torvalds authored
      Merge tag 'platform-drivers-x86-v4.6-3' of git://git.infradead.org/users/dvhart/linux-platform-drivers-x86
      
      Pull x86 platform driver fix from Darren Hart:
       "Fix regression caused by hotkey enabling value in toshiba_acpi"
      
      * tag 'platform-drivers-x86-v4.6-3' of git://git.infradead.org/users/dvhart/linux-platform-drivers-x86:
        toshiba_acpi: Fix regression caused by hotkey enabling value
      9453203b
    • Alexey Brodkin's avatar
      ARC: add support for reserved memory defined by device tree · 1b10cb21
      Alexey Brodkin authored
      Enable reserved memory initialization from device tree.
      Signed-off-by: default avatarAlexey Brodkin <abrodkin@synopsys.com>
      Cc: Grant Likely <grant.likely@linaro.org>
      Cc: Marek Szyprowski <m.szyprowski@samsung.com>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: default avatarVineet Gupta <vgupta@synopsys.com>
      1b10cb21
    • Alexey Brodkin's avatar
      ARC: support generic per-device coherent dma mem · 32ed9a0e
      Alexey Brodkin authored
      Signed-off-by: default avatarAlexey Brodkin <abrodkin@synopsys.com>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: default avatarVineet Gupta <vgupta@synopsys.com>
      32ed9a0e
    • Romain Perier's avatar
      nios2: memset: use the right constraint modifier for the %4 output operand · a8950e49
      Romain Perier authored
      Depending on the size of the area to be memset'ed, the nios2 memset implementation
      either uses a naive loop (for buffers smaller or equal than 8 bytes) or a more optimized
      implementation (for buffers larger than 8 bytes). This implementation does 4-byte stores
      rather than 1-byte stores to speed up memset.
      
      However, we discovered that on our nios2 platform, memset() was not properly setting the
      buffer to the expected value. A memset of 0xff would not set the entire buffer to 0xff, but to:
      
      0xff 0x00 0xff 0x00 0xff 0x00 0xff 0x00 ...
      
      Which is obviously incorrect. Our investigation has revealed that the problem lies in the
      incorrect constraints used in the inline assembly.
      
      The following piece of assembly, from the nios2 memset implementation, is supposed to
      create a 4-byte value that repeats 4 times the 1-byte pattern passed as memset argument:
      
      /* fill8 %3, %5 (c & 0xff) */
      "       slli    %4, %5, 8\n"
      "       or      %4, %4, %5\n"
      "       slli    %3, %4, 16\n"
      "       or      %3, %3, %4\n"
      
      However, depending on the compiler and optimization level, this code might be compiled as:
      
      34:	280a923a 	slli	r5,r5,8
      38:	294ab03a 	or	r5,r5,r5
      3c:	2808943a 	slli	r4,r5,16
      40:	2148b03a 	or	r4,r4,r5
      
      This is wrong because r5 gets used both for %5 and %4, which leads to the final pattern
      stored in r4 to be 0xff00ff00 rather than the expected 0xffffffff.
      
      %4 is defined with the "=r" constraint, i.e as an output operand. However, as explained in
      http://www.ethernut.de/en/documents/arm-inline-asm.html, this does not prevent gcc from
      using the same register for an output operand (%4) and input operand (%5). By using the
      constraint modifier '&', we indicate that the register should be used for output only. With this
      change, we get the following assembly output:
      
      34:	2810923a 	slli	r8,r5,8
      38:	4150b03a 	or	r8,r8,r5
      3c:	400e943a 	slli	r7,r8,16
      40:	3a0eb03a 	or	r7,r7,r8
      
      Which correctly produces the 0xffffffff pattern when 0xff is passed as the memset() pattern.
      
      It is worth mentioning the observed consequence of this bug: we were hitting the kernel
      BUG() in mm/bootmem.c:__free() that verifies when marking a page as free that it was
      previously marked as occupied (i.e that the bit was set to 1). The entire bootmem bitmap is
      set to 0xff bit via a memset() during the bootmem initialization. The bootmem_free() call right
      after the initialization was finding some bits to be set to 0, which didn't make sense since the
      bitmap has just been memset'ed to 0xff. Except that due to the bug explained above, the
      bitmap was in fact initialized to 0xff00ff00.
      
      Thanks to Marek Vasut for his help and feedback.
      Signed-off-by: default avatarRomain Perier <romain.perier@free-electrons.com>
      Acked-by: default avatarMarek Vasut <marex@denx.de>
      Acked-by: default avatarLey Foon Tan <lftan@altera.com>
      a8950e49
  3. 26 Apr, 2016 6 commits
    • Linus Torvalds's avatar
      Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net · f28f20da
      Linus Torvalds authored
      Pull networking fixes from David Miller:
      
       1) Handle v4/v6 mixed sockets properly in soreuseport, from Craig
          Gallak.
      
       2) Bug fixes for the new macsec facility (missing kmalloc NULL checks,
          missing locking around netdev list traversal, etc.) from Sabrina
          Dubroca.
      
       3) Fix handling of host routes on ifdown in ipv6, from David Ahern.
      
       4) Fix double-fdput in bpf verifier.  From Jann Horn.
      
      * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (31 commits)
        bpf: fix double-fdput in replace_map_fd_with_map_ptr()
        net: ipv6: Delete host routes on an ifdown
        Revert "ipv6: Revert optional address flusing on ifdown."
        net/mlx4_en: fix spurious timestamping callbacks
        net: dummy: remove note about being Y by default
        cxgbi: fix uninitialized flowi6
        ipv6: Revert optional address flusing on ifdown.
        ipv4/fib: don't warn when primary address is missing if in_dev is dead
        net/mlx5: Add pci shutdown callback
        net/mlx5_core: Remove static from local variable
        net/mlx5e: Use vport MTU rather than physical port MTU
        net/mlx5e: Fix minimum MTU
        net/mlx5e: Device's mtu field is u16 and not int
        net/mlx5_core: Add ConnectX-5 to list of supported devices
        net/mlx5e: Fix MLX5E_100BASE_T define
        net/mlx5_core: Fix soft lockup in steering error flow
        qlcnic: Update version to 5.3.64
        net: stmmac: socfpga: Remove re-registration of reset controller
        macsec: fix netlink attribute validation
        macsec: add missing macsec prefix in uapi
        ...
      f28f20da
    • Linus Torvalds's avatar
      Merge tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc · 91ea692f
      Linus Torvalds authored
      Pull ARM SoC fixes from Arnd Bergmann:
       "Here are the latest bug fixes for ARM SoCs, mostly addressing recent
        regressions.  Changes are across several platforms, so I'm listing
        every change separately here.
      
        Regressions since 4.5:
      
         - A correction of the psci firmware DT binding, to prevent users from
           relying on unintended semantics
      
         - Actually getting the newly merged clock driver for some OMAP
           platforms to work
      
         - A revert of patches for the Qualcomm BAM, these need to be reworked
           for 4.7 to avoid breaking boards other than the one they were
           intended for
      
         - A correction for the I2C device nodes on the Socionext Uniphier
           platform
      
         - i.MX SDHCI was broken for non-DT platforms due to a change with the
           setting of the DMA mask
      
         - A revert of a patch that accidentally added a nonexisting clock on
           the Rensas "Porter" board
      
         - A couple of OMAP fixes that are all related to suspend after the
           power domain changes for dra7
      
         - On Mediatek, revert part of the power domain initialization changes
           that broke mt8173-evb
      
        Fixes for older bugs:
      
         - Workaround for an "external abort" in the omap34xx suspend/resume
           code.
      
         - The USB1/eSATA should not be listed as an excon device on
           am57xx-beagle-x15 (broken since v4.0)
      
         - A v4.5 regression in the TI AM33xx and AM43XX DT specifying
           incorrect DMA request lines for the GPMC
      
         - The jiffies calibration on Renesas platforms was incorrect for some
           modern CPU cores.
      
         - A hardware errata woraround for clockdomains on TI DRA7"
      
      * tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
        drivers: firmware: psci: unify enable-method binding on ARM {64,32}-bit systems
        arm64: dts: uniphier: fix I2C nodes of PH1-LD20
        ARM: shmobile: timer: Fix preset_lpj leading to too short delays
        Revert "ARM: dts: porter: Enable SCIF_CLK frequency and pins"
        ARM: dts: r8a7791: Don't disable referenced optional clocks
        Revert "ARM: OMAP: Catch callers of revision information prior to it being populated"
        ARM: OMAP3: Fix external abort on 36xx waking from off mode idle
        ARM: dts: am57xx-beagle-x15: remove extcon_usb1
        ARM: dts: am437x: Fix GPMC dma properties
        ARM: dts: am33xx: Fix GPMC dma properties
        Revert "soc: mediatek: SCPSYS: Fix double enabling of regulators"
        ARM: mach-imx: sdhci-esdhc-imx: initialize DMA mask
        ARM: DRA7: clockdomain: Implement timer workaround for errata i874
        ARM: OMAP: Catch callers of revision information prior to it being populated
        ARM: dts: dra7: Correct clock tree for sys_32k_ck
        ARM: OMAP: DRA7: Provide proper class to omap2_set_globals_tap
        ARM: OMAP: DRA7: wakeupgen: Skip SAR save for wakeupgen
        Revert "dts: msm8974: Add dma channels for blsp2_i2c1 node"
        Revert "dts: msm8974: Add blsp2_bam dma node"
        ARM: dts: Add clocks for dm814x ADPLL
      91ea692f
    • Linus Torvalds's avatar
      devpts: more pty driver interface cleanups · 8ead9dd5
      Linus Torvalds authored
      This is more prep-work for the upcoming pty changes.  Still just code
      cleanup with no actual semantic changes.
      
      This removes a bunch pointless complexity by just having the slave pty
      side remember the dentry associated with the devpts slave rather than
      the inode.  That allows us to remove all the "look up the dentry" code
      for when we want to remove it again.
      
      Together with moving the tty pointer from "inode->i_private" to
      "dentry->d_fsdata" and getting rid of pointless inode locking, this
      removes about 30 lines of code.  Not only is the end result smaller,
      it's simpler and easier to understand.
      
      The old code, for example, depended on the d_find_alias() to not just
      find the dentry, but also to check that it is still hashed, which in
      turn validated the tty pointer in the inode.
      
      That is a _very_ roundabout way to say "invalidate the cached tty
      pointer when the dentry is removed".
      
      The new code just does
      
      	dentry->d_fsdata = NULL;
      
      in devpts_pty_kill() instead, invalidating the tty pointer rather more
      directly and obviously.  Don't do something complex and subtle when the
      obvious straightforward approach will do.
      
      The rest of the patch (ie apart from code deletion and the above tty
      pointer clearing) is just switching the calling convention to pass the
      dentry or file pointer around instead of the inode.
      
      Cc: Eric Biederman <ebiederm@xmission.com>
      Cc: Peter Anvin <hpa@zytor.com>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Al Viro <viro@zeniv.linux.org.uk>
      Cc: Peter Hurley <peter@hurleysoftware.com>
      Cc: Serge Hallyn <serge.hallyn@ubuntu.com>
      Cc: Willy Tarreau <w@1wt.eu>
      Cc: Aurelien Jarno <aurelien@aurel32.net>
      Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
      Cc: Jann Horn <jann@thejh.net>
      Cc: Greg KH <greg@kroah.com>
      Cc: Jiri Slaby <jslaby@suse.com>
      Cc: Florian Weimer <fw@deneb.enyo.de>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      8ead9dd5
    • Jann Horn's avatar
      bpf: fix double-fdput in replace_map_fd_with_map_ptr() · 8358b02b
      Jann Horn authored
      When bpf(BPF_PROG_LOAD, ...) was invoked with a BPF program whose bytecode
      references a non-map file descriptor as a map file descriptor, the error
      handling code called fdput() twice instead of once (in __bpf_map_get() and
      in replace_map_fd_with_map_ptr()). If the file descriptor table of the
      current task is shared, this causes f_count to be decremented too much,
      allowing the struct file to be freed while it is still in use
      (use-after-free). This can be exploited to gain root privileges by an
      unprivileged user.
      
      This bug was introduced in
      commit 0246e64d ("bpf: handle pseudo BPF_LD_IMM64 insn"), but is only
      exploitable since
      commit 1be7f75d ("bpf: enable non-root eBPF programs") because
      previously, CAP_SYS_ADMIN was required to reach the vulnerable code.
      
      (posted publicly according to request by maintainer)
      Signed-off-by: default avatarJann Horn <jannh@google.com>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
      Acked-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      8358b02b
    • Hariprasad S's avatar
      RDMA/iw_cxgb4: Fix bar2 virt addr calculation for T4 chips · 32cc92c7
      Hariprasad S authored
      For T4, kernel mode qps don't use the user doorbell. User mode qps during
      flow control db ringing are forced into kernel, where user doorbell is
      treated as kernel doorbell and proper bar2 offset in bar2 virtual space is
      calculated, which incase of T4 is a bogus address, causing a kernel panic
      due to illegal write during doorbell ringing.
      In case of T4, kernel mode qp bar2 virtual address should be 0. Added T4
      check during bar2 virtual address calculation to return 0. Fixed Bar2
      range checks based on bar2 physical address.
      
      The below oops will be fixed
      
        <1>BUG: unable to handle kernel paging request at 000000000002aa08
        <1>IP: [<ffffffffa011d800>] c4iw_uld_control+0x4e0/0x880 [iw_cxgb4]
        <4>PGD 1416a8067 PUD 15bf35067 PMD 0
        <4>Oops: 0002 [#1] SMP
        <4>last sysfs file:
        /sys/devices/pci0000:00/0000:00:03.0/0000:02:00.4/infiniband/cxgb4_0/node_guid
        <4>CPU 5
        <4>Modules linked in: rdma_ucm rdma_cm ib_cm ib_sa ib_mad ib_uverbs
        ip6table_filter ip6_tables ebtable_nat ebtables ipt_MASQUERADE
        iptable_nat nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 xt_state nf_conntrack
        ipt_REJECT xt_CHECKSUM iptable_mangle iptable_filter ip_tables bridge autofs4
        target_core_iblock target_core_file target_core_pscsi target_core_mod
        configfs bnx2fc cnic uio fcoe libfcoe libfc scsi_transport_fc scsi_tgt 8021q
        garp stp llc cpufreq_ondemand acpi_cpufreq freq_table mperf vhost_net macvtap
        macvlan tun kvm uinput microcode iTCO_wdt iTCO_vendor_support sg joydev
        serio_raw i2c_i801 i2c_core lpc_ich mfd_core e1000e ptp pps_core ioatdma dca
        i7core_edac edac_core shpchp ext3 jbd mbcache sd_mod crc_t10dif pata_acpi
        ata_generic ata_piix iw_cxgb4 iw_cm ib_core ib_addr cxgb4 ipv6 dm_mirror
        dm_region_hash dm_log dm_mod [last unloaded: scsi_wait_scan]
        <4>
        Supermicro X8ST3/X8ST3
        <4>RIP: 0010:[<ffffffffa011d800>]  [<ffffffffa011d800>]
        c4iw_uld_control+0x4e0/0x880 [iw_cxgb4]
        <4>RSP: 0000:ffff880155a03db0  EFLAGS: 00010006
        <4>RAX: 000000000000001d RBX: ffff88013ae5fc00 RCX: ffff880155adb180
        <4>RDX: 000000000002aa00 RSI: 0000000000000001 RDI: ffff88013ae5fdf8
        <4>RBP: ffff880155a03e10 R08: 0000000000000000 R09: 0000000000000001
        <4>R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
        <4>R13: 000000000000001d R14: ffff880156414ab0 R15: ffffe8ffffc05b88
        <4>FS:  0000000000000000(0000) GS:ffff8800282a0000(0000) knlGS:0000000000000000
        <4>CS:  0010 DS: 0018 ES: 0018 CR0: 000000008005003b
        <4>CR2: 000000000002aa08 CR3: 000000015bd0e000 CR4: 00000000000007e0
        <4>DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
        <4>DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
        <4>Process cxgb4 (pid: 394, threadinfo ffff880155a00000, task ffff880156414ab0)
        <4>Stack:
        <4> ffff880156415068 ffff880155adb180 ffff880155a03df0 ffffffffa00a344b
        <4><d> 00000000000003e8 ffff880155920000 0000000000000004 ffff880155920000
        <4><d> ffff88015592d438 ffffffffa00a3860 ffff880155a03fd8 ffffe8ffffc05b88
        <4>Call Trace:
        <4> [<ffffffffa00a344b>] ? enable_txq_db+0x2b/0x80 [cxgb4]
        <4> [<ffffffffa00a3860>] ? process_db_full+0x0/0xa0 [cxgb4]
        <4> [<ffffffffa00a38a6>] process_db_full+0x46/0xa0 [cxgb4]
        <4> [<ffffffff8109fda0>] worker_thread+0x170/0x2a0
        <4> [<ffffffff810a6aa0>] ? autoremove_wake_function+0x0/0x40
        <4> [<ffffffff8109fc30>] ? worker_thread+0x0/0x2a0
        <4> [<ffffffff810a660e>] kthread+0x9e/0xc0
        <4> [<ffffffff8100c28a>] child_rip+0xa/0x20
        <4> [<ffffffff810a6570>] ? kthread+0x0/0xc0
        <4> [<ffffffff8100c280>] ? child_rip+0x0/0x20
        <4>Code: e9 ba 00 00 00 66 0f 1f 44 00 00 44 8b 05 29 07 02 00 45 85 c0 0f 85
        71 02 00 00 8b 83 70 01 00 00 45 0f b7 ed c1 e0 0f 44 09 e8 <89> 42 08 0f ae f8
        66 c7 83 82 01 00 00 00 00 44 0f b7 ab dc 01
        <1>RIP  [<ffffffffa011d800>] c4iw_uld_control+0x4e0/0x880 [iw_cxgb4]
        <4> RSP <ffff880155a03db0>
        <4>CR2: 000000000002aa08`
      
      Based on original work by Bharat Potnuri <bharat@chelsio.com>
      
      Fixes: 74217d4c ("iw_cxgb4: support for bar2 qid densities exceeding the page size")
      Signed-off-by: default avatarSteve Wise <swise@opengridcomputing.com>
      Signed-off-by: default avatarHariprasad Shenai <hariprasad@chelsio.com>
      Reviewed-by: default avatarLeon Romanovsky <leon@leon.nu>
      Signed-off-by: default avatarDoug Ledford <dledford@redhat.com>
      32cc92c7
    • Steve Wise's avatar
      iw_cxgb4: handle draining an idle qp · 40edd7fd
      Steve Wise authored
      In c4iw_drain_sq/rq(), if the particular queue is already empty
      then don't block.
      
      Fixes: ce4af14d94aa ('iw_cxgb4: add queue drain functions')
      Signed-off-by: default avatarSteve Wise <swise@opengridcomputing.com>
      Signed-off-by: default avatarDoug Ledford <dledford@redhat.com>
      40edd7fd