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dae55b6fef
linux/drivers
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Julian Wiedmann dae55b6fef s390/qdio: don't retry EQBS after CCQ 96 
Immediate retry of EQBS after CCQ 96 means that we potentially misreport
the state of buffers inspected during the first EQBS call.

This occurs when
1. the first EQBS finds all inspected buffers still in the initial state
   set by the driver (ie INPUT EMPTY or OUTPUT PRIMED),
2. the EQBS terminates early with CCQ 96, and
3. by the time that the second EQBS comes around, the state of those
   previously inspected buffers has changed.

If the state reported by the second EQBS is 'driver-owned', all we know
is that the previous buffers are driver-owned now as well. But we can't
tell if they all have the same state. So for instance
- the second EQBS reports OUTPUT EMPTY, but any number of the previous
  buffers could be OUTPUT ERROR by now,
- the second EQBS reports OUTPUT ERROR, but any number of the previous
  buffers could be OUTPUT EMPTY by now.

Effectively, this can result in both over- and underreporting of errors.

If the state reported by the second EQBS is 'HW-owned', that doesn't
guarantee that the previous buffers have not been switched to
driver-owned in the mean time. So for instance
- the second EQBS reports INPUT EMPTY, but any number of the previous
  buffers could be INPUT PRIMED (or INPUT ERROR) by now.

This would result in failure to process pending work on the queue. If
it's the final check before yielding initiative, this can cause
a (temporary) queue stall due to IRQ avoidance.

Fixes: 25f269f173 ("[S390] qdio: EQBS retry after CCQ 96")
Cc: <stable@vger.kernel.org> #v3.2+
Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Reviewed-by: Benjamin Block <bblock@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2018-03-26 16:12:53 +02:00
..
accessibility
acpi Merge branches 'acpi-ec', 'acpi-tables' and 'acpi-doc' 2018-02-15 12:02:42 +01:00
amba
android vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
ata pci-v4.16-changes 2018-02-06 09:59:40 -08:00
atm atm: he: use 64-bit arithmetic instead of 32-bit 2018-02-08 15:05:16 -05:00
auxdisplay
base ACPI updates for v4.16-rc2 2018-02-15 14:50:32 -08:00
bcma
block Things have been very quiet on the rbd side, as work continues on the 2018-02-08 11:38:59 -08:00
bluetooth vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
bus ARM: SoC driver updates for 4.16 2018-02-01 16:35:31 -08:00
cdrom
char Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-02-14 17:02:15 -08:00
clk MIPS changes for 4.16 2018-02-07 11:22:44 -08:00
clocksource
connector
cpufreq Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-02-14 17:02:15 -08:00
cpuidle powerpc updates for 4.16 2018-02-02 10:01:04 -08:00
crypto Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-02-14 17:02:15 -08:00
dax Merge branch 'for-4.16/dax' into libnvdimm-for-next 2018-02-03 00:26:10 -07:00
dca
devfreq
dio
dma Merge branch 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm 2018-02-02 09:50:51 -08:00
dma-buf vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
edac Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-02-14 17:02:15 -08:00
eisa
extcon
firewire vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
firmware 2nd set of arm64 updates for 4.16: 2018-02-08 10:44:25 -08:00
fmc
fpga
fsi
gpio vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
gpu Merge branch 'linux-4.16' of git://github.com/skeggsb/linux into drm-fixes 2018-02-16 14:26:01 +10:00
hid vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
hsi vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
hv vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
hwmon Fix bad temperature display on Ryzen/Threadripper 2018-02-15 14:31:28 -08:00
hwspinlock
hwtracing Char/Misc driver patches for 4.16-rc1 2018-02-01 10:31:17 -08:00
i2c Merge branch 'i2c/for-4.16' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux 2018-02-04 10:57:43 -08:00
ide pci-v4.16-changes 2018-02-06 09:59:40 -08:00
idle
iio vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
infiniband vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
input vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
iommu IOMMU Updates for Linux v4.16 2018-02-08 12:03:54 -08:00
ipack
irqchip irqchip/bcm: Remove hashed address printing 2018-02-16 14:22:16 +00:00
isdn vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
leds vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
lightnvm
macintosh powerpc/macio: set a proper dma_coherent_mask 2018-02-13 08:58:53 -08:00
mailbox vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
mcb
md dm: correctly handle chained bios in dec_pending() 2018-02-16 10:46:35 -05:00
media vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
memory ARM: SoC driver updates for 4.16 2018-02-01 16:35:31 -08:00
memstick
message
mfd vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
misc powerpc fixes for 4.16 #2 2018-02-14 10:06:41 -08:00
mmc mmc: bcm2835: Don't overwrite max frequency unconditionally 2018-02-14 11:30:10 +01:00
mtd mtd: nand: MTD_NAND_MARVELL should depend on HAS_DMA 2018-02-12 10:57:20 +01:00
mux Char/Misc driver patches for 4.16-rc1 2018-02-01 10:31:17 -08:00
net vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
nfc
ntb NTB: ntb_perf: fix cast to restricted __le32 2018-01-28 22:17:24 -05:00
nubus
nvdimm Merge branch 'for-4.16/nfit' into libnvdimm-for-next 2018-02-03 00:26:26 -07:00
nvme nvme-rdma: fix sysfs invoked reset_ctrl error flow 2018-02-14 15:44:22 +02:00
nvmem
of device property: Constify device_get_match_data() 2018-02-12 10:41:11 +01:00
opp opp: cpu: Replace GFP_ATOMIC with GFP_KERNEL in dev_pm_opp_init_cpufreq_table 2018-02-12 15:07:46 +05:30
oprofile
parisc
parport
pci vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
pcmcia Merge branch 'pcmcia' of git://git.kernel.org/pub/scm/linux/kernel/git/brodo/pcmcia 2018-02-08 11:48:49 -08:00
perf bitmap: replace bitmap_{from,to}_u32array 2018-02-06 18:32:44 -08:00
phy USB/PHY updates for 4.16-rc1 2018-02-01 09:40:49 -08:00
pinctrl This is the bulk of pin control changes for the v4.16 kernel cycle: 2018-02-02 14:22:53 -08:00
platform platform/x86: dell-laptop: Removed duplicates in DMI whitelist 2018-02-15 12:18:33 +02:00
pnp
power power supply and reset changes for the v4.16 series 2018-01-31 12:55:31 -08:00
powercap
pps vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
ps3
ptp vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
pwm
rapidio vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
ras
regulator regulator: Fix suspend to idle 2018-01-30 12:25:59 +00:00
remoteproc remoteproc updates for v4.16 2018-02-05 10:07:40 -08:00
reset
rpmsg vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
rtc vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
s390 s390/qdio: don't retry EQBS after CCQ 96 2018-03-26 16:12:53 +02:00
sbus pci-v4.16-changes 2018-02-06 09:59:40 -08:00
scsi vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
sfi
sh cpufreq: Add and use cpufreq_for_each_{valid_,}entry_idx() 2018-02-08 10:21:39 +01:00
siox
slimbus
sn
soc ARM: SoC driver updates for 4.16 2018-02-01 16:35:31 -08:00
soundwire
spi Merge remote-tracking branch 'spi/topic/xilinx' into spi-next 2018-01-26 17:57:34 +00:00
spmi
ssb Merge git://git.kernel.org/pub/scm/linux/kernel/git/kvalo/wireless-drivers.git 2018-02-01 10:37:39 +02:00
staging irqchip/gic-v3: Ignore disabled ITS nodes 2018-02-16 13:47:58 +00:00
target Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending 2018-02-09 14:49:46 -08:00
tc
tee
thermal Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux 2018-02-06 15:04:58 -08:00
thunderbolt
tty s390/setup : enable display support for KVM guest 2018-03-18 23:01:58 -07:00
uio vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
usb sparc,leon: Select USB_UHCI_BIG_ENDIAN_{MMIO,DESC} 2018-02-15 21:45:16 +00:00
uwb
vfio vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
vhost vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
video s390/setup : enable display support for KVM guest 2018-03-18 23:01:58 -07:00
virt vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
virtio virtio_pci: don't kfree device on register failure 2018-02-01 16:26:45 +02:00
visorbus
vlynq
vme
w1 Documentation updates for 4.16. New stuff includes refcount_t 2018-01-31 19:25:25 -08:00
watchdog linux-watchdog 4.16-rc1 merge window tag 2018-02-07 11:54:34 -08:00
xen pvcalls-front: wait for other operations to return when release passive sockets 2018-02-17 09:41:06 +01:00
zorro
Kconfig Char/Misc driver patches for 4.16-rc1 2018-02-01 10:31:17 -08:00
Makefile pci-v4.16-changes 2018-02-06 09:59:40 -08:00