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Revision 10f1d5d111e8aed46a0f1179faf9a3cf422f689e authored by Joe Thornber on 27 June 2014, 19:29:04 UTC, committed by Mike Snitzer on 10 July 2014, 20:44:14 UTC 
dm io: fix a race condition in the wake up code for sync_io
 
There's a race condition between the atomic_dec_and_test(&io->count)
in dec_count() and the waking of the sync_io() thread.  If the thread
is spuriously woken immediately after the decrement it may exit,
making the on stack io struct invalid, yet the dec_count could still
be using it.

Fix this race by using a completion in sync_io() and dec_count().

Reported-by: Minfei Huang <huangminfei@ucloud.cn>
Signed-off-by: Joe Thornber <thornber@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
1 parent bf14299
Raw File
mkmakefile 
#!/bin/sh
# Generates a small Makefile used in the root of the output
# directory, to allow make to be started from there.
# The Makefile also allow for more convinient build of external modules

# Usage
# $1 - Kernel src directory
# $2 - Output directory
# $3 - version
# $4 - patchlevel


test ! -r $2/Makefile -o -O $2/Makefile || exit 0
# Only overwrite automatically generated Makefiles
# (so we do not overwrite kernel Makefile)
if test -e $2/Makefile && ! grep -q Automatically $2/Makefile
then
	exit 0
fi
if [ "${quiet}" != "silent_" ]; then
	echo "  GEN     $2/Makefile"
fi

cat << EOF > $2/Makefile
# Automatically generated by $0: don't edit

VERSION = $3
PATCHLEVEL = $4

lastword = \$(word \$(words \$(1)),\$(1))
makedir := \$(dir \$(call lastword,\$(MAKEFILE_LIST)))

ifeq ("\$(origin V)", "command line")
VERBOSE := \$(V)
endif
ifneq (\$(VERBOSE),1)
Q := @
endif

MAKEARGS := -C $1
MAKEARGS += O=\$(if \$(patsubst /%,,\$(makedir)),\$(CURDIR)/)\$(patsubst %/,%,\$(makedir))

MAKEFLAGS += --no-print-directory

.PHONY: __sub-make \$(MAKECMDGOALS)

__sub-make:
	\$(Q)\$(MAKE) \$(MAKEARGS) \$(MAKECMDGOALS)

\$(filter-out __sub-make, \$(MAKECMDGOALS)): __sub-make
	@:
EOF
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