Re: [PATCH v2 3/3] libxc: do some retries in xc_cpupool_removecpu() for EBUSY case

[Juergen Gross <jgross@suse.com>]

On 01/03/16 12:58, Wei Liu wrote:
> On Tue, Mar 01, 2016 at 10:02:13AM +0100, Juergen Gross wrote:
>> The hypervisor might return EBUSY when trying to remove a cpu from a
>> cpupool when a domain running in this cpupool has pinned a vcpu
>> temporarily. Do some retries in this case, perhaps the situation
>> cleans up.
>>
>> Signed-off-by: Juergen Gross <jgross@suse.com>
>> ---
>>  tools/libxc/xc_cpupool.c | 13 ++++++++++++-
>>  1 file changed, 12 insertions(+), 1 deletion(-)
>>
>> diff --git a/tools/libxc/xc_cpupool.c b/tools/libxc/xc_cpupool.c
>> index c42273e..9f2f95c 100644
>> --- a/tools/libxc/xc_cpupool.c
>> +++ b/tools/libxc/xc_cpupool.c
>> @@ -20,8 +20,11 @@
>>   */
>>  
>>  #include <stdarg.h>
>> +#include <unistd.h>
>>  #include "xc_private.h"
>>  
>> +#define LIBXC_BUSY_RETRIES 5
>> +
>>  static int do_sysctl_save(xc_interface *xch, struct xen_sysctl *sysctl)
>>  {
>>      int ret;
>> @@ -141,13 +144,21 @@ int xc_cpupool_removecpu(xc_interface *xch,
>>                           uint32_t poolid,
>>                           int cpu)
>>  {
>> +    unsigned retries;
>> +    int err;
>>      DECLARE_SYSCTL;
>>  
>>      sysctl.cmd = XEN_SYSCTL_cpupool_op;
>>      sysctl.u.cpupool_op.op = XEN_SYSCTL_CPUPOOL_OP_RMCPU;
>>      sysctl.u.cpupool_op.cpupool_id = poolid;
>>      sysctl.u.cpupool_op.cpu = (cpu < 0) ? XEN_SYSCTL_CPUPOOL_PAR_ANY : cpu;
>> -    return do_sysctl_save(xch, &sysctl);
>> +    for (retries = 0; retries < LIBXC_BUSY_RETRIES; retries++) {
> 
> Libxc coding style requires spaces between ().

Oops, sorry.

> 
>> +        err = do_sysctl_save(xch, &sysctl);
>> +        if (err >= 0 || errno != EBUSY)
> 
> Ditto.
> 
>> +            break;
>> +        sleep(1);
>> +    }
>> +    return err;
>>  }
>>  
>>  int xc_cpupool_movedomain(xc_interface *xch,


Juergen


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