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The setjmp() function doesn't specify whether signal masks are saved and
restored; on Linux they are not, but on BSD (including MacOSX) they are.
We want to have consistent behaviour across platforms, so we should
always use "don't save/restore signal mask" (this is also generally
going to be faster). This also works around a bug in MacOSX where the
signal-restoration on longjmp() affects the signal mask for a completely
different thread, not just the mask for the thread which did the longjmp.
The most visible effect of this was that ctrl-C was ignored on MacOSX
because the CPU thread did a longjmp which resulted in its signal mask
being applied to every thread, so that all threads had SIGINT and SIGTERM
blocked.
The POSIX-sanctioned portable way to do a jump without affecting signal
masks is to siglongjmp() to a sigjmp_buf which was created by calling
sigsetjmp() with a zero savemask parameter, so change all uses of
setjmp()/longjmp() accordingly. [Technically POSIX allows sigsetjmp(buf, 0)
to save the signal mask; however the following siglongjmp() must not
restore the signal mask, so the pair can be effectively considered as
"sigjmp/longjmp which don't touch the mask".]
For Windows we provide a trivial sigsetjmp/siglongjmp in terms of
setjmp/longjmp -- this is OK because no user will ever pass a non-zero
savemask.
The setjmp() uses in tests/tcg/test-i386.c and tests/tcg/linux-test.c
are left untouched because these are self-contained singlethreaded
test programs intended to be run under QEMU's Linux emulation, so they
have neither the portability nor the multithreading issues to deal with.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Tested-by: Stefan Weil <sw@weilnetz.de>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Use the POSIX-specified stack_t type as the argument to sigaltstack()
rather than the legacy struct sigaltstack. This allows us to compile
on MacOSX with --with-coroutine=sigaltstack.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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* kwolf/for-anthony:
qemu-img: Fix segmentation fault
qcow2: Don't ignore failure to clear autoclear flags
coroutine: Fix setup of sigaltstack coroutines
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Use pthread_kill instead of process-wide kill to invoke the signal
handler used for stack switching. This may fix spurious lock-ups with
this backend, easily triggerable by extending the time window between
kill and sigsuspend.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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These were identified using: http://github.com/lyda/misspell-check
and run like this to create a bourne shell script using GNU sed's
-i option:
git ls-files|grep -vF .bin | misspellings -f - |grep -v '^ERROR:' |perl \
-pe 's/^(.*?)\[(\d+)\]: (\w+) -> "(.*?)"$/sed -i '\''${2}s!$3!$4!'\'' $1/'
Manually eliding the FP, "rela->real" and resolving "addres" to
address (not "adders") we get this:
sed -i '450s!thru!through!' Changelog
sed -i '260s!neccessary!necessary!' coroutine-sigaltstack.c
sed -i '54s!miniscule!minuscule!' disas.c
sed -i '1094s!thru!through!' hw/usb/hcd-ehci.c
sed -i '1095s!thru!through!' hw/usb/hcd-ehci.c
sed -i '21s!unecessary!unnecessary!' qapi-schema-guest.json
sed -i '307s!explictly!explicitly!' qemu-ga.c
sed -i '490s!preceeding!preceding!' qga/commands-posix.c
sed -i '792s!addres!address!' qga/commands-posix.c
sed -i '6s!beeing!being!' tests/tcg/test-mmap.c
Also, manually fix "arithmentic", spotted by Peter Maydell:
sed -i 's!arithmentic!arithmetic!' coroutine-sigaltstack.c
Signed-off-by: Jim Meyering <meyering@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
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This file is based in both coroutine-ucontext.c and
pth_mctx.c (from the GNU Portable Threads library).
The mechanism used to change stacks is the sigaltstack
function (variant 2 of the pth library).
v2: Some corrections. Moving global variables into
thread storage (CoroutineThreadState).
Signed-off-by: Alex Barcelo <abarcelo@ac.upc.edu>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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