* [PATCH v1 24/25] kvm/eventfd: Use sequence counter with associated spinlock
[not found] <20200519214547.352050-1-a.darwish@linutronix.de>
@ 2020-05-19 21:45 ` Ahmed S. Darwish
[not found] ` <20200608005729.1874024-1-a.darwish@linutronix.de>
[not found] ` <20200630054452.3675847-1-a.darwish@linutronix.de>
2 siblings, 0 replies; 4+ messages in thread
From: Ahmed S. Darwish @ 2020-05-19 21:45 UTC (permalink / raw)
To: Peter Zijlstra, Ingo Molnar, Will Deacon
Cc: Thomas Gleixner, Paul E. McKenney, Sebastian A. Siewior,
Steven Rostedt, LKML, Ahmed S. Darwish, Paolo Bonzini, kvm
A sequence counter write side critical section must be protected by some
form of locking to serialize writers. A plain seqcount_t does not
contain the information of which lock must be held when entering a write
side critical section.
Use the new seqcount_spinlock_t data type, which allows to associate a
spinlock with the sequence counter. This enables lockdep to verify that
the spinlock used for writer serialization is held when the write side
critical section is entered.
If lockdep is disabled this lock association is compiled out and has
neither storage size nor runtime overhead.
Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
---
include/linux/kvm_irqfd.h | 2 +-
virt/kvm/eventfd.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/include/linux/kvm_irqfd.h b/include/linux/kvm_irqfd.h
index dc1da020305b..dac047abdba7 100644
--- a/include/linux/kvm_irqfd.h
+++ b/include/linux/kvm_irqfd.h
@@ -42,7 +42,7 @@ struct kvm_kernel_irqfd {
wait_queue_entry_t wait;
/* Update side is protected by irqfds.lock */
struct kvm_kernel_irq_routing_entry irq_entry;
- seqcount_t irq_entry_sc;
+ seqcount_spinlock_t irq_entry_sc;
/* Used for level IRQ fast-path */
int gsi;
struct work_struct inject;
diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index 67b6fc153e9c..8694a2920ea9 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -303,7 +303,7 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
INIT_LIST_HEAD(&irqfd->list);
INIT_WORK(&irqfd->inject, irqfd_inject);
INIT_WORK(&irqfd->shutdown, irqfd_shutdown);
- seqcount_init(&irqfd->irq_entry_sc);
+ seqcount_spinlock_init(&irqfd->irq_entry_sc, &kvm->irqfds.lock);
f = fdget(args->fd);
if (!f.file) {
--
2.20.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH v2 17/18] kvm/eventfd: Use sequence counter with associated spinlock
[not found] ` <20200608005729.1874024-1-a.darwish@linutronix.de>
@ 2020-06-08 0:57 ` Ahmed S. Darwish
2020-06-08 12:57 ` Paolo Bonzini
0 siblings, 1 reply; 4+ messages in thread
From: Ahmed S. Darwish @ 2020-06-08 0:57 UTC (permalink / raw)
To: Peter Zijlstra, Ingo Molnar, Will Deacon
Cc: Thomas Gleixner, Paul E. McKenney, Sebastian A. Siewior,
Steven Rostedt, LKML, Ahmed S. Darwish, Paolo Bonzini, kvm
A sequence counter write side critical section must be protected by some
form of locking to serialize writers. A plain seqcount_t does not
contain the information of which lock must be held when entering a write
side critical section.
Use the new seqcount_spinlock_t data type, which allows to associate a
spinlock with the sequence counter. This enables lockdep to verify that
the spinlock used for writer serialization is held when the write side
critical section is entered.
If lockdep is disabled this lock association is compiled out and has
neither storage size nor runtime overhead.
Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
---
include/linux/kvm_irqfd.h | 2 +-
virt/kvm/eventfd.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/include/linux/kvm_irqfd.h b/include/linux/kvm_irqfd.h
index dc1da020305b..dac047abdba7 100644
--- a/include/linux/kvm_irqfd.h
+++ b/include/linux/kvm_irqfd.h
@@ -42,7 +42,7 @@ struct kvm_kernel_irqfd {
wait_queue_entry_t wait;
/* Update side is protected by irqfds.lock */
struct kvm_kernel_irq_routing_entry irq_entry;
- seqcount_t irq_entry_sc;
+ seqcount_spinlock_t irq_entry_sc;
/* Used for level IRQ fast-path */
int gsi;
struct work_struct inject;
diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index 67b6fc153e9c..8694a2920ea9 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -303,7 +303,7 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
INIT_LIST_HEAD(&irqfd->list);
INIT_WORK(&irqfd->inject, irqfd_inject);
INIT_WORK(&irqfd->shutdown, irqfd_shutdown);
- seqcount_init(&irqfd->irq_entry_sc);
+ seqcount_spinlock_init(&irqfd->irq_entry_sc, &kvm->irqfds.lock);
f = fdget(args->fd);
if (!f.file) {
--
2.20.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v2 17/18] kvm/eventfd: Use sequence counter with associated spinlock
2020-06-08 0:57 ` [PATCH v2 17/18] " Ahmed S. Darwish
@ 2020-06-08 12:57 ` Paolo Bonzini
0 siblings, 0 replies; 4+ messages in thread
From: Paolo Bonzini @ 2020-06-08 12:57 UTC (permalink / raw)
To: Ahmed S. Darwish, Peter Zijlstra, Ingo Molnar, Will Deacon
Cc: Thomas Gleixner, Paul E. McKenney, Sebastian A. Siewior,
Steven Rostedt, LKML, kvm
On 08/06/20 02:57, Ahmed S. Darwish wrote:
> A sequence counter write side critical section must be protected by some
> form of locking to serialize writers. A plain seqcount_t does not
> contain the information of which lock must be held when entering a write
> side critical section.
>
> Use the new seqcount_spinlock_t data type, which allows to associate a
> spinlock with the sequence counter. This enables lockdep to verify that
> the spinlock used for writer serialization is held when the write side
> critical section is entered.
>
> If lockdep is disabled this lock association is compiled out and has
> neither storage size nor runtime overhead.
>
> Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
> ---
> include/linux/kvm_irqfd.h | 2 +-
> virt/kvm/eventfd.c | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/kvm_irqfd.h b/include/linux/kvm_irqfd.h
> index dc1da020305b..dac047abdba7 100644
> --- a/include/linux/kvm_irqfd.h
> +++ b/include/linux/kvm_irqfd.h
> @@ -42,7 +42,7 @@ struct kvm_kernel_irqfd {
> wait_queue_entry_t wait;
> /* Update side is protected by irqfds.lock */
> struct kvm_kernel_irq_routing_entry irq_entry;
> - seqcount_t irq_entry_sc;
> + seqcount_spinlock_t irq_entry_sc;
> /* Used for level IRQ fast-path */
> int gsi;
> struct work_struct inject;
> diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
> index 67b6fc153e9c..8694a2920ea9 100644
> --- a/virt/kvm/eventfd.c
> +++ b/virt/kvm/eventfd.c
> @@ -303,7 +303,7 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
> INIT_LIST_HEAD(&irqfd->list);
> INIT_WORK(&irqfd->inject, irqfd_inject);
> INIT_WORK(&irqfd->shutdown, irqfd_shutdown);
> - seqcount_init(&irqfd->irq_entry_sc);
> + seqcount_spinlock_init(&irqfd->irq_entry_sc, &kvm->irqfds.lock);
>
> f = fdget(args->fd);
> if (!f.file) {
>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH v3 19/20] kvm/eventfd: Use sequence counter with associated spinlock
[not found] ` <20200630054452.3675847-1-a.darwish@linutronix.de>
@ 2020-06-30 5:44 ` Ahmed S. Darwish
0 siblings, 0 replies; 4+ messages in thread
From: Ahmed S. Darwish @ 2020-06-30 5:44 UTC (permalink / raw)
To: Peter Zijlstra, Ingo Molnar, Will Deacon
Cc: Thomas Gleixner, Paul E. McKenney, Sebastian A. Siewior,
Steven Rostedt, LKML, Ahmed S. Darwish, Paolo Bonzini, kvm
A sequence counter write side critical section must be protected by some
form of locking to serialize writers. A plain seqcount_t does not
contain the information of which lock must be held when entering a write
side critical section.
Use the new seqcount_spinlock_t data type, which allows to associate a
spinlock with the sequence counter. This enables lockdep to verify that
the spinlock used for writer serialization is held when the write side
critical section is entered.
If lockdep is disabled this lock association is compiled out and has
neither storage size nor runtime overhead.
Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
---
include/linux/kvm_irqfd.h | 2 +-
virt/kvm/eventfd.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/include/linux/kvm_irqfd.h b/include/linux/kvm_irqfd.h
index dc1da020305b..dac047abdba7 100644
--- a/include/linux/kvm_irqfd.h
+++ b/include/linux/kvm_irqfd.h
@@ -42,7 +42,7 @@ struct kvm_kernel_irqfd {
wait_queue_entry_t wait;
/* Update side is protected by irqfds.lock */
struct kvm_kernel_irq_routing_entry irq_entry;
- seqcount_t irq_entry_sc;
+ seqcount_spinlock_t irq_entry_sc;
/* Used for level IRQ fast-path */
int gsi;
struct work_struct inject;
diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index ef7ed916ad4a..d6408bb497dc 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -303,7 +303,7 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
INIT_LIST_HEAD(&irqfd->list);
INIT_WORK(&irqfd->inject, irqfd_inject);
INIT_WORK(&irqfd->shutdown, irqfd_shutdown);
- seqcount_init(&irqfd->irq_entry_sc);
+ seqcount_spinlock_init(&irqfd->irq_entry_sc, &kvm->irqfds.lock);
f = fdget(args->fd);
if (!f.file) {
--
2.20.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
end of thread, other threads:[~2020-06-30 5:46 UTC | newest]
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[not found] <20200519214547.352050-1-a.darwish@linutronix.de>
2020-05-19 21:45 ` [PATCH v1 24/25] kvm/eventfd: Use sequence counter with associated spinlock Ahmed S. Darwish
[not found] ` <20200608005729.1874024-1-a.darwish@linutronix.de>
2020-06-08 0:57 ` [PATCH v2 17/18] " Ahmed S. Darwish
2020-06-08 12:57 ` Paolo Bonzini
[not found] ` <20200630054452.3675847-1-a.darwish@linutronix.de>
2020-06-30 5:44 ` [PATCH v3 19/20] " Ahmed S. Darwish
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