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Dexuan Cui 35a88a18d7 PCI: hv: Disable/enable IRQs rather than BH in hv_compose_msi_msg() 
Commit de0aa7b2f9 ("PCI: hv: Fix 2 hang issues in hv_compose_msi_msg()")
uses local_bh_disable()/enable(), because hv_pci_onchannelcallback() can
also run in tasklet context as the channel event callback, so bottom halves
should be disabled to prevent a race condition.

With CONFIG_PROVE_LOCKING=y in the recent mainline, or old kernels that
don't have commit f71b74bca6 ("irq/softirqs: Use lockdep to assert IRQs
are disabled/enabled"), when the upper layer IRQ code calls
hv_compose_msi_msg() with local IRQs disabled, we'll see a warning at the
beginning of __local_bh_enable_ip():

  IRQs not enabled as expected
    WARNING: CPU: 0 PID: 408 at kernel/softirq.c:162 __local_bh_enable_ip

The warning exposes an issue in de0aa7b2f97d: local_bh_enable() can
potentially call do_softirq(), which is not supposed to run when local IRQs
are disabled. Let's fix this by using local_irq_save()/restore() instead.

Note: hv_pci_onchannelcallback() is not a hot path because it's only called
when the PCI device is hot added and removed, which is infrequent.

Fixes: de0aa7b2f9 ("PCI: hv: Fix 2 hang issues in hv_compose_msi_msg()")
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Cc: stable@vger.kernel.org
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: K. Y. Srinivasan <kys@microsoft.com>
 		2018-07-09 13:16:07 -05:00
Documentation for-linus-20180616 2018-06-17 05:37:55 +09:00
LICENSES LICENSES: Add Linux-OpenIB license text 2018-04-27 16:41:53 -06:00
arch PCI: controller: Move PCI_DOMAINS selection to arch Kconfig 2018-06-26 15:37:37 -05:00
block for-linus-20180616 2018-06-17 05:37:55 +09:00
certs docs: Fix some broken references 2018-06-15 18:10:01 -03:00
crypto docs: Fix some broken references 2018-06-15 18:10:01 -03:00
drivers PCI: hv: Disable/enable IRQs rather than BH in hv_compose_msi_msg() 2018-07-09 13:16:07 -05:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs Solve a series of broken links for files under Documentation: 2018-06-17 05:25:18 +09:00
include for-linus-20180616 2018-06-17 05:37:55 +09:00
init Kbuild updates for v4.18 (2nd) 2018-06-13 08:40:34 -07:00
ipc ipc: use new return type vm_fault_t 2018-06-15 07:55:25 +09:00
kernel Solve a series of broken links for files under Documentation: 2018-06-17 05:25:18 +09:00
lib docs: Fix some broken references 2018-06-15 18:10:01 -03:00
mm mm: fix oom_kill event handling 2018-06-15 07:55:25 +09:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-06-16 07:39:34 +09:00
samples VFIO updates for v4.18 2018-06-12 13:11:26 -07:00
scripts scripts/documentation-file-ref-check: check tools/*/Documentation 2018-06-15 18:10:01 -03:00
security docs: Fix some broken references 2018-06-15 18:10:01 -03:00
sound docs: Fix some broken references 2018-06-15 18:10:01 -03:00
tools Solve a series of broken links for files under Documentation: 2018-06-17 05:25:18 +09:00
usr kbuild: rename built-in.o to built-in.a 2018-03-26 02:01:19 +09:00
virt - Error path bug fix for overflow tests (Dan) 2018-06-12 18:28:00 -07:00
.clang-format clang-format: add configuration file 2018-04-11 10:28:35 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
…
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap Merge branch 'asoc-4.17' into asoc-4.18 for compress dependencies 2018-04-26 12:24:28 +01:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS/CREDITS: Drop METAG ARCHITECTURE 2018-03-05 16:34:24 +00:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: add basic helper macros to scripts/Kconfig.include 2018-05-29 03:31:19 +09:00
MAINTAINERS Solve a series of broken links for files under Documentation: 2018-06-17 05:25:18 +09:00
Makefile Linux 4.18-rc1 2018-06-17 08:04:49 +09:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -06:00

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.
See Documentation/00-INDEX for a list of what is contained in each file.

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.