Re: [Xen-devel] [PATCH v4 1/3] libxc: do some retries in xc_cpupool_removecpu() for EBUSY case

[Olaf Hering <olaf@xxxxxxxxx>]

On Thu, Mar 10, Juergen Gross wrote:

> +#define NUM_RMCPU_BUSY_RETRIES 5
> +
>  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 < NUM_RMCPU_BUSY_RETRIES; retries++ ) {
> +        err = do_sysctl_save(xch, &sysctl);
> +        if ( err < 0 && errno == EBUSY )
> +            sleep(1);
> +        else
> +            break;
> +    }
> +    return err;

This may fail with gcc-4.8, at least with -Og in 13.1:

[  105s] xc_cpupool.c: In function 'xc_cpupool_removecpu':
[  105s] xc_cpupool.c:168:5: error: 'err' may be used uninitialized in this 
function [-Werror=maybe-uninitialized]
[  105s]      return err;
[  105s]      ^


Olaf

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