On 11/23/18 11:24 AM, Juergen Gross wrote:
> Failure of an element of a Xen multicall is signalled via a WARN()
> only unless the kernel is compiled with MC_DEBUG. It is impossible to
s/unless/if
> know which element failed and why it did so.
>
> Change that by printing the related information even without MC_DEBUG,
> even if maybe in some limited form (e.g. without information which
> caller produced the failing element).
>
> Move the printing out of the switch statement in order to have the
> same information for a single call.
>
> Signed-off-by: Juergen Gross <jgr...@suse.com>
> ---
> arch/x86/xen/multicalls.c | 35 ++++++++++++++++++++---------------
> 1 file changed, 20 insertions(+), 15 deletions(-)
>
> diff --git a/arch/x86/xen/multicalls.c b/arch/x86/xen/multicalls.c
> index 2bce7958ce8b..0766a08bdf45 100644
> --- a/arch/x86/xen/multicalls.c
> +++ b/arch/x86/xen/multicalls.c
> @@ -69,6 +69,11 @@ void xen_mc_flush(void)
>
> trace_xen_mc_flush(b->mcidx, b->argidx, b->cbidx);
>
> +#if MC_DEBUG
> + memcpy(b->debug, b->entries,
> + b->mcidx * sizeof(struct multicall_entry));
> +#endif
> +
> switch (b->mcidx) {
> case 0:
> /* no-op */
> @@ -87,32 +92,34 @@ void xen_mc_flush(void)
> break;
>
> default:
> -#if MC_DEBUG
> - memcpy(b->debug, b->entries,
> - b->mcidx * sizeof(struct multicall_entry));
> -#endif
> -
> if (HYPERVISOR_multicall(b->entries, b->mcidx) != 0)
> BUG();
> for (i = 0; i < b->mcidx; i++)
> if (b->entries[i].result < 0)
> ret++;
> + }
>
> + if (WARN_ON(ret)) {
> + pr_err("%d of %d multicall(s) failed: cpu %d\n",
> + ret, b->mcidx, smp_processor_id());
> + for (i = 0; i < b->mcidx; i++) {
> + if (b->entries[i].result < 0) {
> #if MC_DEBUG
> - if (ret) {
> - printk(KERN_ERR "%d multicall(s) failed: cpu %d\n",
> - ret, smp_processor_id());
> - dump_stack();
> - for (i = 0; i < b->mcidx; i++) {
> - printk(KERN_DEBUG " call %2d/%d: op=%lu
> arg=[%lx] result=%ld\t%pF\n",
> - i+1, b->mcidx,
> + pr_err(" call %2d: op=%lu arg=[%lx]
> result=%ld\t%pF\n",
> + i + 1,
> b->debug[i].op,
> b->debug[i].args[0],
> b->entries[i].result,
> b->caller[i]);
> +#else
> + pr_err(" call %2d: op=%lu arg=[%lx]
> result=%ld\n",
> + i + 1,
> + b->entries[i].op,
> + b->entries[i].args[0],
> + b->entries[i].result);
> +#endif
Doesn't (non-debug) hypervisor corrupt op and args?
(Also, we don't really need to print anything when b->entries[i].result
== 0)
-boris
> }
> }
> -#endif
> }
>
> b->mcidx = 0;
> @@ -126,8 +133,6 @@ void xen_mc_flush(void)
> b->cbidx = 0;
>
> local_irq_restore(flags);
> -
> - WARN_ON(ret);
> }
>
> struct multicall_space __xen_mc_entry(size_t args)
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