diff mbox series

migration: use parameters.mode in cpr_state_save

Message ID 1738788841-211843-1-git-send-email-steven.sistare@oracle.com (mailing list archive)
State New
Headers show
Series migration: use parameters.mode in cpr_state_save | expand

Commit Message

Steven Sistare Feb. 5, 2025, 8:54 p.m. UTC
qmp_migrate guarantees that cpr_channel is not null for
MIG_MODE_CPR_TRANSFER when cpr_state_save is called:

    qmp_migrate()
        if (s->parameters.mode == MIG_MODE_CPR_TRANSFER && !cpr_channel) {
            return;
        }
        cpr_state_save(cpr_channel)

but cpr_state_save checks for mode differently before using channel,
and Coverity cannot infer that they are equivalent in outgoing QEMU,
and warns that channel may be NULL:

    cpr_state_save(channel)
        MigMode mode = migrate_mode();
        if (mode == MIG_MODE_CPR_TRANSFER) {
            f = cpr_transfer_output(channel, errp);

To make Coverity happy, use parameters.mode in cpr_state_save.

Resolves: Coverity CID 1590980
Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
---
 migration/cpr.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

Peter Xu Feb. 5, 2025, 9:28 p.m. UTC | #1
On Wed, Feb 05, 2025 at 12:54:01PM -0800, Steve Sistare wrote:
> qmp_migrate guarantees that cpr_channel is not null for
> MIG_MODE_CPR_TRANSFER when cpr_state_save is called:
> 
>     qmp_migrate()
>         if (s->parameters.mode == MIG_MODE_CPR_TRANSFER && !cpr_channel) {
>             return;
>         }
>         cpr_state_save(cpr_channel)
> 
> but cpr_state_save checks for mode differently before using channel,
> and Coverity cannot infer that they are equivalent in outgoing QEMU,
> and warns that channel may be NULL:
> 
>     cpr_state_save(channel)
>         MigMode mode = migrate_mode();
>         if (mode == MIG_MODE_CPR_TRANSFER) {
>             f = cpr_transfer_output(channel, errp);
> 
> To make Coverity happy, use parameters.mode in cpr_state_save.
> 
> Resolves: Coverity CID 1590980
> Reported-by: Peter Maydell <peter.maydell@linaro.org>
> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
> ---
>  migration/cpr.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/migration/cpr.c b/migration/cpr.c
> index 584b0b9..7f20bd5 100644
> --- a/migration/cpr.c
> +++ b/migration/cpr.c
> @@ -8,6 +8,7 @@
>  #include "qemu/osdep.h"
>  #include "qapi/error.h"
>  #include "migration/cpr.h"
> +#include "migration/migration.h"
>  #include "migration/misc.h"
>  #include "migration/options.h"
>  #include "migration/qemu-file.h"
> @@ -132,7 +133,7 @@ int cpr_state_save(MigrationChannel *channel, Error **errp)
>  {
>      int ret;
>      QEMUFile *f;
> -    MigMode mode = migrate_mode();
> +    MigMode mode = migrate_get_current()->parameters.mode;

Are we sure this can make coverity happy?

Another more straightforward change is caching migrate mode in
qmp_migrate() and also check that before invoking cpr_state_save().

Thanks,

>  
>      trace_cpr_state_save(MigMode_str(mode));
>  
> -- 
> 1.8.3.1
>
Steven Sistare Feb. 5, 2025, 9:52 p.m. UTC | #2
On 2/5/2025 4:28 PM, Peter Xu wrote:
> On Wed, Feb 05, 2025 at 12:54:01PM -0800, Steve Sistare wrote:
>> qmp_migrate guarantees that cpr_channel is not null for
>> MIG_MODE_CPR_TRANSFER when cpr_state_save is called:
>>
>>      qmp_migrate()
>>          if (s->parameters.mode == MIG_MODE_CPR_TRANSFER && !cpr_channel) {
>>              return;
>>          }
>>          cpr_state_save(cpr_channel)
>>
>> but cpr_state_save checks for mode differently before using channel,
>> and Coverity cannot infer that they are equivalent in outgoing QEMU,
>> and warns that channel may be NULL:
>>
>>      cpr_state_save(channel)
>>          MigMode mode = migrate_mode();
>>          if (mode == MIG_MODE_CPR_TRANSFER) {
>>              f = cpr_transfer_output(channel, errp);
>>
>> To make Coverity happy, use parameters.mode in cpr_state_save.
>>
>> Resolves: Coverity CID 1590980
>> Reported-by: Peter Maydell <peter.maydell@linaro.org>
>> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
>> ---
>>   migration/cpr.c | 3 ++-
>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/migration/cpr.c b/migration/cpr.c
>> index 584b0b9..7f20bd5 100644
>> --- a/migration/cpr.c
>> +++ b/migration/cpr.c
>> @@ -8,6 +8,7 @@
>>   #include "qemu/osdep.h"
>>   #include "qapi/error.h"
>>   #include "migration/cpr.h"
>> +#include "migration/migration.h"
>>   #include "migration/misc.h"
>>   #include "migration/options.h"
>>   #include "migration/qemu-file.h"
>> @@ -132,7 +133,7 @@ int cpr_state_save(MigrationChannel *channel, Error **errp)
>>   {
>>       int ret;
>>       QEMUFile *f;
>> -    MigMode mode = migrate_mode();
>> +    MigMode mode = migrate_get_current()->parameters.mode;
> 
> Are we sure this can make coverity happy?

It should, based on Peter Maydell's analysis, but I would appreciate
if he could apply and test the fix.

> Another more straightforward change is caching migrate mode in
> qmp_migrate() and also check that before invoking cpr_state_save().

Surely anyone would consider my one-line change to be straight forward.

- Steve

>>       trace_cpr_state_save(MigMode_str(mode));
>>   
>> -- 
>> 1.8.3.1
>>
>
diff mbox series

Patch

diff --git a/migration/cpr.c b/migration/cpr.c
index 584b0b9..7f20bd5 100644
--- a/migration/cpr.c
+++ b/migration/cpr.c
@@ -8,6 +8,7 @@ 
 #include "qemu/osdep.h"
 #include "qapi/error.h"
 #include "migration/cpr.h"
+#include "migration/migration.h"
 #include "migration/misc.h"
 #include "migration/options.h"
 #include "migration/qemu-file.h"
@@ -132,7 +133,7 @@  int cpr_state_save(MigrationChannel *channel, Error **errp)
 {
     int ret;
     QEMUFile *f;
-    MigMode mode = migrate_mode();
+    MigMode mode = migrate_get_current()->parameters.mode;
 
     trace_cpr_state_save(MigMode_str(mode));