[Xen-devel] xen/console: Fix build when CONFIG_DEBUG_TRACE=y

Message ID 20190819180125.17504-1-julien.grall@arm.com
State New
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  • [Xen-devel] xen/console: Fix build when CONFIG_DEBUG_TRACE=y
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Commit Message

Julien Grall Aug. 19, 2019, 6:01 p.m.
Commit b5e6e1ee8da "xen/console: Don't treat NUL character as the end
of the buffer" extended sercon_puts to take the number of character
to print in argument.

Sadly, a couple of couple of the callers in debugtrace_dump_worker()
were not converted. This result to a build failure when enabling
CONFIG_DEBUG_TRACE.

Spotted by Travis using randconfig
Signed-off-by: Julien Grall <julien.grall@arm.com>
---
 xen/drivers/char/console.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Comments

Andrew Cooper Aug. 19, 2019, 6:04 p.m. | #1
On 19/08/2019 19:01, Julien Grall wrote:
> Commit b5e6e1ee8da "xen/console: Don't treat NUL character as the end
> of the buffer" extended sercon_puts to take the number of character
> to print in argument.
>
> Sadly, a couple of couple of the callers in debugtrace_dump_worker()
> were not converted. This result to a build failure when enabling
> CONFIG_DEBUG_TRACE.
>
> Spotted by Travis using randconfig
> Signed-off-by: Julien Grall <julien.grall@arm.com>
> ---
>  xen/drivers/char/console.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c
> index 2c14c2ca73..924d4971ca 100644
> --- a/xen/drivers/char/console.c
> +++ b/xen/drivers/char/console.c
> @@ -1185,11 +1185,12 @@ static void debugtrace_dump_worker(void)
>  
>      /* Print oldest portion of the ring. */
>      ASSERT(debugtrace_buf[debugtrace_bytes - 1] == 0);
> -    sercon_puts(&debugtrace_buf[debugtrace_prd]);
> +    sercon_puts(&debugtrace_buf[debugtrace_prd],
> +                strlen(&debugtrace_buf[debugtrace_prd]));

Isn't this just debugtrace_bytes - debugtrace_prd - 1 ?

~Andrew

>  
>      /* Print youngest portion of the ring. */
>      debugtrace_buf[debugtrace_prd] = '\0';
> -    sercon_puts(&debugtrace_buf[0]);
> +    sercon_puts(&debugtrace_buf[0], debugtrace_prd);
>  
>      memset(debugtrace_buf, '\0', debugtrace_bytes);
>
Julien Grall Aug. 19, 2019, 6:37 p.m. | #2
Hi Andrew,

On 8/19/19 7:04 PM, Andrew Cooper wrote:
> On 19/08/2019 19:01, Julien Grall wrote:
>> Commit b5e6e1ee8da "xen/console: Don't treat NUL character as the end
>> of the buffer" extended sercon_puts to take the number of character
>> to print in argument.
>>
>> Sadly, a couple of couple of the callers in debugtrace_dump_worker()
>> were not converted. This result to a build failure when enabling
>> CONFIG_DEBUG_TRACE.
>>
>> Spotted by Travis using randconfig
>> Signed-off-by: Julien Grall <julien.grall@arm.com>
>> ---
>>   xen/drivers/char/console.c | 5 +++--
>>   1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c
>> index 2c14c2ca73..924d4971ca 100644
>> --- a/xen/drivers/char/console.c
>> +++ b/xen/drivers/char/console.c
>> @@ -1185,11 +1185,12 @@ static void debugtrace_dump_worker(void)
>>   
>>       /* Print oldest portion of the ring. */
>>       ASSERT(debugtrace_buf[debugtrace_bytes - 1] == 0);
>> -    sercon_puts(&debugtrace_buf[debugtrace_prd]);
>> +    sercon_puts(&debugtrace_buf[debugtrace_prd],
>> +                strlen(&debugtrace_buf[debugtrace_prd]));
> 
> Isn't this just debugtrace_bytes - debugtrace_prd - 1 ?

I tried and it resulted to print a lot of @^ on the console. This is 
because the ring may not be full.

So the portion between debugtrace_prd and debugtrace_bytes will be full 
of zero.

Looking at the code again, I think this portion and either be full of 
zero character or full of non-zero character. In other word, a mix would 
not be possible. So how about:

if ( debugtrace_buf[debugtrace_prd] != '\0' )
   sercon_puts(&debugtrace_buf[debugtrace_prd],
               debugtrace_bytes - debugtrace_prd - 1);


Cheers,
Andrew Cooper Aug. 20, 2019, 1:12 p.m. | #3
On 19/08/2019 19:37, Julien Grall wrote:
> Hi Andrew,
>
> On 8/19/19 7:04 PM, Andrew Cooper wrote:
>> On 19/08/2019 19:01, Julien Grall wrote:
>>> Commit b5e6e1ee8da "xen/console: Don't treat NUL character as the end
>>> of the buffer" extended sercon_puts to take the number of character
>>> to print in argument.
>>>
>>> Sadly, a couple of couple of the callers in debugtrace_dump_worker()
>>> were not converted. This result to a build failure when enabling
>>> CONFIG_DEBUG_TRACE.
>>>
>>> Spotted by Travis using randconfig
>>> Signed-off-by: Julien Grall <julien.grall@arm.com>
>>> ---
>>>   xen/drivers/char/console.c | 5 +++--
>>>   1 file changed, 3 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c
>>> index 2c14c2ca73..924d4971ca 100644
>>> --- a/xen/drivers/char/console.c
>>> +++ b/xen/drivers/char/console.c
>>> @@ -1185,11 +1185,12 @@ static void debugtrace_dump_worker(void)
>>>         /* Print oldest portion of the ring. */
>>>       ASSERT(debugtrace_buf[debugtrace_bytes - 1] == 0);
>>> -    sercon_puts(&debugtrace_buf[debugtrace_prd]);
>>> +    sercon_puts(&debugtrace_buf[debugtrace_prd],
>>> +                strlen(&debugtrace_buf[debugtrace_prd]));
>>
>> Isn't this just debugtrace_bytes - debugtrace_prd - 1 ?
>
> I tried and it resulted to print a lot of @^ on the console. This is
> because the ring may not be full.
>
> So the portion between debugtrace_prd and debugtrace_bytes will be
> full of zero.
>
> Looking at the code again, I think this portion and either be full of
> zero character or full of non-zero character. In other word, a mix
> would not be possible. So how about:
>
> if ( debugtrace_buf[debugtrace_prd] != '\0' )
>   sercon_puts(&debugtrace_buf[debugtrace_prd],
>               debugtrace_bytes - debugtrace_prd - 1);

LGTM.  Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Julien Grall Aug. 21, 2019, 5:30 p.m. | #4
Hi,

On 20/08/2019 14:12, Andrew Cooper wrote:
> On 19/08/2019 19:37, Julien Grall wrote:
>> Hi Andrew,
>>
>> On 8/19/19 7:04 PM, Andrew Cooper wrote:
>>> On 19/08/2019 19:01, Julien Grall wrote:
>>>> Commit b5e6e1ee8da "xen/console: Don't treat NUL character as the end
>>>> of the buffer" extended sercon_puts to take the number of character
>>>> to print in argument.
>>>>
>>>> Sadly, a couple of couple of the callers in debugtrace_dump_worker()
>>>> were not converted. This result to a build failure when enabling
>>>> CONFIG_DEBUG_TRACE.
>>>>
>>>> Spotted by Travis using randconfig
>>>> Signed-off-by: Julien Grall <julien.grall@arm.com>
>>>> ---
>>>>    xen/drivers/char/console.c | 5 +++--
>>>>    1 file changed, 3 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c
>>>> index 2c14c2ca73..924d4971ca 100644
>>>> --- a/xen/drivers/char/console.c
>>>> +++ b/xen/drivers/char/console.c
>>>> @@ -1185,11 +1185,12 @@ static void debugtrace_dump_worker(void)
>>>>          /* Print oldest portion of the ring. */
>>>>        ASSERT(debugtrace_buf[debugtrace_bytes - 1] == 0);
>>>> -    sercon_puts(&debugtrace_buf[debugtrace_prd]);
>>>> +    sercon_puts(&debugtrace_buf[debugtrace_prd],
>>>> +                strlen(&debugtrace_buf[debugtrace_prd]));
>>>
>>> Isn't this just debugtrace_bytes - debugtrace_prd - 1 ?
>>
>> I tried and it resulted to print a lot of @^ on the console. This is
>> because the ring may not be full.
>>
>> So the portion between debugtrace_prd and debugtrace_bytes will be
>> full of zero.
>>
>> Looking at the code again, I think this portion and either be full of
>> zero character or full of non-zero character. In other word, a mix
>> would not be possible. So how about:
>>
>> if ( debugtrace_buf[debugtrace_prd] != '\0' )
>>    sercon_puts(&debugtrace_buf[debugtrace_prd],
>>                debugtrace_bytes - debugtrace_prd - 1);
> 
> LGTM.  Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>

Thank you! I will update the patch and commit it.

Cheers,

Patch

diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c
index 2c14c2ca73..924d4971ca 100644
--- a/xen/drivers/char/console.c
+++ b/xen/drivers/char/console.c
@@ -1185,11 +1185,12 @@  static void debugtrace_dump_worker(void)
 
     /* Print oldest portion of the ring. */
     ASSERT(debugtrace_buf[debugtrace_bytes - 1] == 0);
-    sercon_puts(&debugtrace_buf[debugtrace_prd]);
+    sercon_puts(&debugtrace_buf[debugtrace_prd],
+                strlen(&debugtrace_buf[debugtrace_prd]));
 
     /* Print youngest portion of the ring. */
     debugtrace_buf[debugtrace_prd] = '\0';
-    sercon_puts(&debugtrace_buf[0]);
+    sercon_puts(&debugtrace_buf[0], debugtrace_prd);
 
     memset(debugtrace_buf, '\0', debugtrace_bytes);