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Brian Norris 25733c4e67 ath10k: pci: use mutex for diagnostic window CE polling 
The DIAG copy engine is only used via polling, but it holds a spinlock
with softirqs disabled. Each iteration of our read/write loops can
theoretically take 20ms (two 10ms timeout loops), and this loop can be
run an unbounded number of times while holding the spinlock -- dependent
on the request size given by the caller.

As of commit 39501ea641 ("ath10k: download firmware via diag Copy
Engine for QCA6174 and QCA9377."), we transfer large chunks of firmware
memory using this mechanism. With large enough firmware segments, this
becomes an exceedingly long period for disabling soft IRQs. For example,
with a 500KiB firmware segment, in testing QCA6174A, I see 200 loop
iterations of about 50-100us each, which can total about 10-20ms.

In reality, we don't really need to block softirqs for this duration.
The DIAG CE is only used in polling mode, and we only need to hold
ce_lock to make sure any CE bookkeeping is done without screwing up
another CE. Otherwise, we only need to ensure exclusion between
ath10k_pci_diag_{read,write}_mem() contexts.

This patch moves to use fine-grained locking for the shared ce_lock,
while adding a new mutex just to ensure mutual exclusion of diag
read/write operations.

Tested on QCA6174A, firmware version WLAN.RM.4.4.1-00132-QCARMSWPZ-1.

Fixes: 39501ea641 ("ath10k: download firmware via diag Copy Engine for QCA6174 and QCA9377.")
Signed-off-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
2019-02-11 18:31:55 +02:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2019-02-06 16:56:20 -08:00
block Revert "block: cover another queue enter recursion via BIO_QUEUE_ENTERED" 2019-01-27 06:35:28 -07:00
certs
crypto
Documentation Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2019-02-06 16:56:20 -08:00
drivers ath10k: pci: use mutex for diagnostic window CE polling 2019-02-11 18:31:55 +02:00
firmware
fs socket: Rename SO_RCVTIMEO/ SO_SNDTIMEO with _OLD suffixes 2019-02-03 11:17:31 -08:00
include Third batch of iwlwifi patches intended for v5.1 2019-02-07 11:34:26 +02:00
init
ipc
kernel bpf: introduce BPF_F_LOCK flag 2019-02-01 20:55:39 +01:00
lib
LICENSES
mm Revert "mm, memory_hotplug: initialize struct pages for the full memory section" 2019-01-28 10:35:22 -08:00
net Merge branch 'for_net-next-5.1/rds-tos-v4' of git://git.kernel.org/pub/scm/linux/kernel/git/ssantosh/linux 2019-02-06 17:00:15 -08:00
samples samples/bpf: Check the prog id before exiting 2019-02-01 23:37:51 +01:00
scripts
security
sound sound fixes for 5.0-rc4 2019-01-25 05:55:26 +13:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2019-02-06 16:56:20 -08:00
usr
virt
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/kvalo/wireless-drivers.git 2019-02-08 14:14:35 +02:00
Makefile Linux 5.0-rc4 2019-01-27 15:18:05 -08:00
README

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.