[PATCH] migration: use parameters.mode in cpr_state_save

[PATCH] migration: use parameters.mode in cpr_state_save

[Steve Sistare]

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;
 
     trace_cpr_state_save(MigMode_str(mode));
 
-- 
1.8.3.1

Re: [PATCH] migration: use parameters.mode in cpr_state_save

[Peter Xu]

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
> 

-- 
Peter Xu

Re: [PATCH] migration: use parameters.mode in cpr_state_save

[Steven Sistare]

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
>>
> 

Re: [PATCH] migration: use parameters.mode in cpr_state_save

[Steven Sistare]

On 2/5/2025 4:52 PM, Steven Sistare wrote:
> 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.


Given that Coverity complains about channel, and not mode, this is the
most direct fix:

----------------------------------------
diff --git a/migration/cpr.c b/migration/cpr.c
index 59644e8..224b6ff 100644
--- a/migration/cpr.c
+++ b/migration/cpr.c
@@ -160,6 +160,7 @@ int cpr_state_save(MigrationChannel *channel, Error **errp)
      trace_cpr_state_save(MigMode_str(mode));

      if (mode == MIG_MODE_CPR_TRANSFER) {
+        g_assert(channel);
          f = cpr_transfer_output(channel, errp);
      } else {
          return 0;
-------------------------------

- Steve

Re: [PATCH] migration: use parameters.mode in cpr_state_save

[Fabiano Rosas]

Steven Sistare <steven.sistare@oracle.com> writes:

> On 2/5/2025 4:52 PM, Steven Sistare wrote:
>> 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.
>
>
> Given that Coverity complains about channel, and not mode, this is the
> most direct fix:
>
> ----------------------------------------
> diff --git a/migration/cpr.c b/migration/cpr.c
> index 59644e8..224b6ff 100644
> --- a/migration/cpr.c
> +++ b/migration/cpr.c
> @@ -160,6 +160,7 @@ int cpr_state_save(MigrationChannel *channel, Error **errp)
>       trace_cpr_state_save(MigMode_str(mode));
>
>       if (mode == MIG_MODE_CPR_TRANSFER) {
> +        g_assert(channel);
>           f = cpr_transfer_output(channel, errp);
>       } else {
>           return 0;
> -------------------------------
>
> - Steve

Queueing this^ version. Thanks