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2ac2a7d4d9
linux/arch/x86/xen
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Juergen Gross 2ac2a7d4d9 xen: fix race in xen_qlock_wait() 
In the following situation a vcpu waiting for a lock might not be
woken up from xen_poll_irq():

CPU 1:                CPU 2:                      CPU 3:
takes a spinlock
                      tries to get lock
                      -> xen_qlock_wait()
frees the lock
-> xen_qlock_kick(cpu2)
                        -> xen_clear_irq_pending()

takes lock again
                                                  tries to get lock
                                                  -> *lock = _Q_SLOW_VAL
                        -> *lock == _Q_SLOW_VAL ?
                        -> xen_poll_irq()
frees the lock
-> xen_qlock_kick(cpu3)

And cpu 2 will sleep forever.

This can be avoided easily by modifying xen_qlock_wait() to call
xen_poll_irq() only if the related irq was not pending and to call
xen_clear_irq_pending() only if it was pending.

Cc: stable@vger.kernel.org
Cc: Waiman.Long@hp.com
Cc: peterz@infradead.org
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
2018-10-24 10:17:38 +02:00
..
apic.c Merge branch 'WIP.x86/asm' into x86/urgent, because the topic is ready 2018-04-12 09:42:34 +02:00
debugfs.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
debugfs.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
efi.c x86/xen: Add SPDX identifier in arch/x86/xen files 2018-09-03 16:50:33 +02:00
enlighten_hvm.c x86/xen: Add SPDX identifier in arch/x86/xen files 2018-09-03 16:50:33 +02:00
enlighten_pv.c x86/paravirt: Use a single ops structure 2018-09-03 16:50:35 +02:00
enlighten_pvh.c Merge branch 'x86-grub2-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-10-23 16:31:33 +01:00
enlighten.c Merge branch 'x86-paravirt-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-10-23 17:54:58 +01:00
grant-table.c x86/xen: Add SPDX identifier in arch/x86/xen files 2018-09-03 16:50:33 +02:00
irq.c x86/paravirt: Use a single ops structure 2018-09-03 16:50:35 +02:00
Kconfig Merge branch 'x86-paravirt-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-10-23 17:54:58 +01:00
Makefile x86/xen: Link platform-pci-unplug.o only if CONFIG_XEN_PVHVM 2018-09-03 16:50:33 +02:00
mmu_hvm.c x86/paravirt: Use a single ops structure 2018-09-03 16:50:35 +02:00
mmu_pv.c Merge branch 'x86-paravirt-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-10-23 17:54:58 +01:00
mmu.c x86/xen: Add SPDX identifier in arch/x86/xen files 2018-09-03 16:50:33 +02:00
mmu.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
multicalls.c xen: don't use privcmd_call() from xen_mc_flush() 2018-08-07 11:37:01 -04:00
multicalls.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
p2m.c x86/xen: Add SPDX identifier in arch/x86/xen files 2018-09-03 16:50:33 +02:00
pci-swiotlb-xen.c x86/xen: Add SPDX identifier in arch/x86/xen files 2018-09-03 16:50:33 +02:00
platform-pci-unplug.c Merge branch 'x86-paravirt-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-10-23 17:54:58 +01:00
pmu.c Merge branch 'x86-cpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-10-23 16:16:40 +01:00
pmu.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
setup.c x86/xen: remove unused function xen_auto_xlated_memory_setup() 2018-08-20 14:46:18 -04:00
smp_hvm.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
smp_pv.c x86/stackprotector: Remove the call to boot_init_stack_canary() from cpu_startup_entry() 2018-10-22 04:07:24 +02:00
smp.c x86/xen: Calculate __max_logical_packages on PV domains 2018-02-17 09:40:45 +01:00
smp.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
spinlock.c xen: fix race in xen_qlock_wait() 2018-10-24 10:17:38 +02:00
suspend_hvm.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
suspend_pv.c x86/xen/time: Initialize pv xen time in init_hypervisor_platform() 2018-07-20 00:02:39 +02:00
suspend.c x86/xen: Zero MSR_IA32_SPEC_CTRL before suspend 2018-02-28 16:03:19 +01:00
time.c x86/paravirt: Use a single ops structure 2018-09-03 16:50:35 +02:00
trace.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
vdso.h x86/xen: Add SPDX identifier in arch/x86/xen files 2018-09-03 16:50:33 +02:00
vga.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
xen-asm_32.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
xen-asm_64.S x86/entry/64: Use the TSS sp2 slot for SYSCALL/SYSRET scratch space 2018-09-08 11:20:11 +02:00
xen-asm.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
xen-head.S xen/pvh: Indicate XENFEAT_linux_rsdp_unrestricted to Xen 2018-04-10 09:22:22 -04:00
xen-ops.h x86/xen: remove unused function xen_auto_xlated_memory_setup() 2018-08-20 14:46:18 -04:00
xen-pvh.S x86/xen: Add SPDX identifier in arch/x86/xen files 2018-09-03 16:50:33 +02:00