* [PATCH] memory: remove incorrect RCU comment for address_space_read()
@ 2021-09-09 14:10 Stefan Hajnoczi
2021-09-09 16:35 ` Philippe Mathieu-Daudé
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: Stefan Hajnoczi @ 2021-09-09 14:10 UTC (permalink / raw)
To: qemu-devel; +Cc: Paolo Bonzini, Stefan Hajnoczi, Peter Xu, David Hildenbrand
Although the doc comment says "Called within RCU critical section" the
address_space_read() function takes the RCU read lock itself. There is
no need for the caller to hold an RCU read lock.
Cc: Paolo Bonzini <pbonzini@redhat.com>
Fixes: b2a44fcad74f1cc7a6786d38eba7db12ab2352ba ("address_space_read: address_space_to_flatview needs RCU lock")
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
include/exec/memory.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/exec/memory.h b/include/exec/memory.h
index c3d417d317..60508a1e19 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -2768,7 +2768,7 @@ static inline bool memory_access_is_direct(MemoryRegion *mr, bool is_write)
*
* Return a MemTxResult indicating whether the operation succeeded
* or failed (eg unassigned memory, device rejected the transaction,
- * IOMMU fault). Called within RCU critical section.
+ * IOMMU fault).
*
* @as: #AddressSpace to be accessed
* @addr: address within that address space
--
2.31.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] memory: remove incorrect RCU comment for address_space_read()
2021-09-09 14:10 [PATCH] memory: remove incorrect RCU comment for address_space_read() Stefan Hajnoczi
@ 2021-09-09 16:35 ` Philippe Mathieu-Daudé
2021-09-09 16:43 ` David Hildenbrand
2021-09-12 6:54 ` Paolo Bonzini
2 siblings, 0 replies; 4+ messages in thread
From: Philippe Mathieu-Daudé @ 2021-09-09 16:35 UTC (permalink / raw)
To: Stefan Hajnoczi, qemu-devel; +Cc: Paolo Bonzini, Peter Xu, David Hildenbrand
On 9/9/21 4:10 PM, Stefan Hajnoczi wrote:
> Although the doc comment says "Called within RCU critical section" the
> address_space_read() function takes the RCU read lock itself. There is
> no need for the caller to hold an RCU read lock.
>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Fixes: b2a44fcad74f1cc7a6786d38eba7db12ab2352ba ("address_space_read: address_space_to_flatview needs RCU lock")
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
> include/exec/memory.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] memory: remove incorrect RCU comment for address_space_read()
2021-09-09 14:10 [PATCH] memory: remove incorrect RCU comment for address_space_read() Stefan Hajnoczi
2021-09-09 16:35 ` Philippe Mathieu-Daudé
@ 2021-09-09 16:43 ` David Hildenbrand
2021-09-12 6:54 ` Paolo Bonzini
2 siblings, 0 replies; 4+ messages in thread
From: David Hildenbrand @ 2021-09-09 16:43 UTC (permalink / raw)
To: Stefan Hajnoczi, qemu-devel; +Cc: Paolo Bonzini, Peter Xu
On 09.09.21 16:10, Stefan Hajnoczi wrote:
> Although the doc comment says "Called within RCU critical section" the
> address_space_read() function takes the RCU read lock itself. There is
> no need for the caller to hold an RCU read lock.
>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Fixes: b2a44fcad74f1cc7a6786d38eba7db12ab2352ba ("address_space_read: address_space_to_flatview needs RCU lock")
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
> include/exec/memory.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index c3d417d317..60508a1e19 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -2768,7 +2768,7 @@ static inline bool memory_access_is_direct(MemoryRegion *mr, bool is_write)
> *
> * Return a MemTxResult indicating whether the operation succeeded
> * or failed (eg unassigned memory, device rejected the transaction,
> - * IOMMU fault). Called within RCU critical section.
> + * IOMMU fault).
> *
> * @as: #AddressSpace to be accessed
> * @addr: address within that address space
>
Reviewed-by: David Hildenbrand <david@redhat.com>
--
Thanks,
David / dhildenb
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] memory: remove incorrect RCU comment for address_space_read()
2021-09-09 14:10 [PATCH] memory: remove incorrect RCU comment for address_space_read() Stefan Hajnoczi
2021-09-09 16:35 ` Philippe Mathieu-Daudé
2021-09-09 16:43 ` David Hildenbrand
@ 2021-09-12 6:54 ` Paolo Bonzini
2 siblings, 0 replies; 4+ messages in thread
From: Paolo Bonzini @ 2021-09-12 6:54 UTC (permalink / raw)
To: Stefan Hajnoczi, qemu-devel; +Cc: Peter Xu, David Hildenbrand
On 09/09/21 16:10, Stefan Hajnoczi wrote:
> Although the doc comment says "Called within RCU critical section" the
> address_space_read() function takes the RCU read lock itself. There is
> no need for the caller to hold an RCU read lock.
>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Fixes: b2a44fcad74f1cc7a6786d38eba7db12ab2352ba ("address_space_read: address_space_to_flatview needs RCU lock")
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
> include/exec/memory.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index c3d417d317..60508a1e19 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -2768,7 +2768,7 @@ static inline bool memory_access_is_direct(MemoryRegion *mr, bool is_write)
> *
> * Return a MemTxResult indicating whether the operation succeeded
> * or failed (eg unassigned memory, device rejected the transaction,
> - * IOMMU fault). Called within RCU critical section.
> + * IOMMU fault).
> *
> * @as: #AddressSpace to be accessed
> * @addr: address within that address space
>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
^ permalink raw reply [flat|nested] 4+ messages in thread
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2021-09-09 14:10 [PATCH] memory: remove incorrect RCU comment for address_space_read() Stefan Hajnoczi
2021-09-09 16:35 ` Philippe Mathieu-Daudé
2021-09-09 16:43 ` David Hildenbrand
2021-09-12 6:54 ` Paolo Bonzini
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