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[PATCH] colo: fix return without releasing RCU

Paolo Bonzini posted 1 patch 4 years, 4 months ago
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git fetch https://github.com/patchew-project/qemu tags/patchew/1576246112-23406-2-git-send-email-pbonzini@redhat.com
Maintainers: Juan Quintela <quintela@redhat.com>, "Dr. David Alan Gilbert" <dgilbert@redhat.com>
migration/ram.c | 33 +++++++++++++++++----------------
1 file changed, 17 insertions(+), 16 deletions(-)
[PATCH] colo: fix return without releasing RCU
Posted by Paolo Bonzini 4 years, 4 months ago 
Use WITH_RCU_READ_LOCK_GUARD to avoid exiting colo_init_ram_cache
without releasing RCU.

Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 migration/ram.c | 33 +++++++++++++++++----------------
 1 file changed, 17 insertions(+), 16 deletions(-)

diff --git a/migration/ram.c b/migration/ram.c
index 7dd7f81..8d7c015 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -3891,26 +3891,27 @@ int colo_init_ram_cache(void)
 {
     RAMBlock *block;
 
-    rcu_read_lock();
-    RAMBLOCK_FOREACH_NOT_IGNORED(block) {
-        block->colo_cache = qemu_anon_ram_alloc(block->used_length,
-                                                NULL,
-                                                false);
-        if (!block->colo_cache) {
-            error_report("%s: Can't alloc memory for COLO cache of block %s,"
-                         "size 0x" RAM_ADDR_FMT, __func__, block->idstr,
-                         block->used_length);
-            RAMBLOCK_FOREACH_NOT_IGNORED(block) {
-                if (block->colo_cache) {
-                    qemu_anon_ram_free(block->colo_cache, block->used_length);
-                    block->colo_cache = NULL;
+    WITH_RCU_READ_LOCK_GUARD() {
+        RAMBLOCK_FOREACH_NOT_IGNORED(block) {
+            block->colo_cache = qemu_anon_ram_alloc(block->used_length,
+                                                    NULL,
+                                                    false);
+            if (!block->colo_cache) {
+                error_report("%s: Can't alloc memory for COLO cache of block %s,"
+                             "size 0x" RAM_ADDR_FMT, __func__, block->idstr,
+                             block->used_length);
+                RAMBLOCK_FOREACH_NOT_IGNORED(block) {
+                    if (block->colo_cache) {
+                        qemu_anon_ram_free(block->colo_cache, block->used_length);
+                        block->colo_cache = NULL;
+                    }
                 }
+                return -errno;
             }
-            return -errno;
+            memcpy(block->colo_cache, block->host, block->used_length);
         }
-        memcpy(block->colo_cache, block->host, block->used_length);
     }
-    rcu_read_unlock();
+
     /*
     * Record the dirty pages that sent by PVM, we use this dirty bitmap together
     * with to decide which page in cache should be flushed into SVM's RAM. Here
-- 
1.8.3.1
Re: [PATCH] colo: fix return without releasing RCU
Posted by Dr. David Alan Gilbert 4 years, 4 months ago 
* Paolo Bonzini (pbonzini@redhat.com) wrote:
> Use WITH_RCU_READ_LOCK_GUARD to avoid exiting colo_init_ram_cache
> without releasing RCU.
> 
> Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> ---
>  migration/ram.c | 33 +++++++++++++++++----------------
>  1 file changed, 17 insertions(+), 16 deletions(-)
> 
> diff --git a/migration/ram.c b/migration/ram.c
> index 7dd7f81..8d7c015 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -3891,26 +3891,27 @@ int colo_init_ram_cache(void)
>  {
>      RAMBlock *block;
>  
> -    rcu_read_lock();
> -    RAMBLOCK_FOREACH_NOT_IGNORED(block) {
> -        block->colo_cache = qemu_anon_ram_alloc(block->used_length,
> -                                                NULL,
> -                                                false);
> -        if (!block->colo_cache) {
> -            error_report("%s: Can't alloc memory for COLO cache of block %s,"
> -                         "size 0x" RAM_ADDR_FMT, __func__, block->idstr,
> -                         block->used_length);
> -            RAMBLOCK_FOREACH_NOT_IGNORED(block) {
> -                if (block->colo_cache) {
> -                    qemu_anon_ram_free(block->colo_cache, block->used_length);
> -                    block->colo_cache = NULL;
> +    WITH_RCU_READ_LOCK_GUARD() {
> +        RAMBLOCK_FOREACH_NOT_IGNORED(block) {
> +            block->colo_cache = qemu_anon_ram_alloc(block->used_length,
> +                                                    NULL,
> +                                                    false);
> +            if (!block->colo_cache) {
> +                error_report("%s: Can't alloc memory for COLO cache of block %s,"
> +                             "size 0x" RAM_ADDR_FMT, __func__, block->idstr,
> +                             block->used_length);
> +                RAMBLOCK_FOREACH_NOT_IGNORED(block) {
> +                    if (block->colo_cache) {
> +                        qemu_anon_ram_free(block->colo_cache, block->used_length);
> +                        block->colo_cache = NULL;
> +                    }
>                  }
> +                return -errno;
>              }
> -            return -errno;
> +            memcpy(block->colo_cache, block->host, block->used_length);
>          }
> -        memcpy(block->colo_cache, block->host, block->used_length);
>      }
> -    rcu_read_unlock();
> +
>      /*
>      * Record the dirty pages that sent by PVM, we use this dirty bitmap together
>      * with to decide which page in cache should be flushed into SVM's RAM. Here
> -- 
> 1.8.3.1
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
Re: [PATCH] colo: fix return without releasing RCU
Posted by Zhang, Chen 4 years, 4 months ago 
On 12/13/2019 11:03 PM, Dr. David Alan Gilbert wrote:
> * Paolo Bonzini (pbonzini@redhat.com) wrote:
>> Use WITH_RCU_READ_LOCK_GUARD to avoid exiting colo_init_ram_cache
>> without releasing RCU.
>>
>> Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Reviewed-by: Zhang Chen <chen.zhang@intel.com>


>
>> ---
>>   migration/ram.c | 33 +++++++++++++++++----------------
>>   1 file changed, 17 insertions(+), 16 deletions(-)
>>
>> diff --git a/migration/ram.c b/migration/ram.c
>> index 7dd7f81..8d7c015 100644
>> --- a/migration/ram.c
>> +++ b/migration/ram.c
>> @@ -3891,26 +3891,27 @@ int colo_init_ram_cache(void)
>>   {
>>       RAMBlock *block;
>>   
>> -    rcu_read_lock();
>> -    RAMBLOCK_FOREACH_NOT_IGNORED(block) {
>> -        block->colo_cache = qemu_anon_ram_alloc(block->used_length,
>> -                                                NULL,
>> -                                                false);
>> -        if (!block->colo_cache) {
>> -            error_report("%s: Can't alloc memory for COLO cache of block %s,"
>> -                         "size 0x" RAM_ADDR_FMT, __func__, block->idstr,
>> -                         block->used_length);
>> -            RAMBLOCK_FOREACH_NOT_IGNORED(block) {
>> -                if (block->colo_cache) {
>> -                    qemu_anon_ram_free(block->colo_cache, block->used_length);
>> -                    block->colo_cache = NULL;
>> +    WITH_RCU_READ_LOCK_GUARD() {
>> +        RAMBLOCK_FOREACH_NOT_IGNORED(block) {
>> +            block->colo_cache = qemu_anon_ram_alloc(block->used_length,
>> +                                                    NULL,
>> +                                                    false);
>> +            if (!block->colo_cache) {
>> +                error_report("%s: Can't alloc memory for COLO cache of block %s,"
>> +                             "size 0x" RAM_ADDR_FMT, __func__, block->idstr,
>> +                             block->used_length);
>> +                RAMBLOCK_FOREACH_NOT_IGNORED(block) {
>> +                    if (block->colo_cache) {
>> +                        qemu_anon_ram_free(block->colo_cache, block->used_length);
>> +                        block->colo_cache = NULL;
>> +                    }
>>                   }
>> +                return -errno;
>>               }
>> -            return -errno;
>> +            memcpy(block->colo_cache, block->host, block->used_length);
>>           }
>> -        memcpy(block->colo_cache, block->host, block->used_length);
>>       }
>> -    rcu_read_unlock();
>> +
>>       /*
>>       * Record the dirty pages that sent by PVM, we use this dirty bitmap together
>>       * with to decide which page in cache should be flushed into SVM's RAM. Here
>> -- 
>> 1.8.3.1
>>
> --
> Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
>

Patchew 2.1-devel-0870f84

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