Re: [Qemu-devel] [PATCH 03/10] pseries: Clean up hash page table allocation error handling

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 01/15/2016 11:00 PM, David Gibson wrote:
> The spapr_alloc_htab() and spapr_reset_htab() functions currently handle
> all errors with error_setg(&error_abort, ...).
>
> But really, the callers are really better placed to decide on the error
> handling.  So, instead make the functions use the error propagation
> infrastructure.
>
> In the callers we change to &error_fatal instead of &error_abort, since
> this can be triggered by a bad configuration or kernel error rather than
> indicating a programming error in qemu.
>
> While we're at it improve the messages themselves a bit, and clean up the
> indentation a little.
>
> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> ---
>   hw/ppc/spapr.c | 24 ++++++++++++++++--------
>   1 file changed, 16 insertions(+), 8 deletions(-)
>
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index b7fd09a..d28e349 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -1016,7 +1016,7 @@ static void emulate_spapr_hypercall(PowerPCCPU *cpu)
>   #define CLEAN_HPTE(_hpte)  ((*(uint64_t *)(_hpte)) &= tswap64(~HPTE64_V_HPTE_DIRTY))
>   #define DIRTY_HPTE(_hpte)  ((*(uint64_t *)(_hpte)) |= tswap64(HPTE64_V_HPTE_DIRTY))
>
> -static void spapr_alloc_htab(sPAPRMachineState *spapr)
> +static void spapr_alloc_htab(sPAPRMachineState *spapr, Error **errp)
>   {
>       long shift;
>       int index;
> @@ -1031,7 +1031,8 @@ static void spapr_alloc_htab(sPAPRMachineState *spapr)
>            * For HV KVM, host kernel will return -ENOMEM when requested
>            * HTAB size can't be allocated.
>            */
> -        error_setg(&error_abort, "Failed to allocate HTAB of requested size, try with smaller maxmem");
> +        error_setg_errno(errp, -shift,
> +                         "Error allocating KVM hash page table, try smaller maxmem");
>       } else if (shift > 0) {
>           /*
>            * Kernel handles htab, we don't need to allocate one
> @@ -1040,7 +1041,10 @@ static void spapr_alloc_htab(sPAPRMachineState *spapr)
>            * but we don't allow booting of such guests.
>            */
>           if (shift != spapr->htab_shift) {
> -            error_setg(&error_abort, "Failed to allocate HTAB of requested size, try with smaller maxmem");
> +            error_setg(errp,
> +                "Small allocation for KVM hash page table (%ld < %"
> +                PRIu32 "), try smaller maxmem",



Even though it is not in the CODING_STYLE, I have not seen anyone objecting 
the very good kernel's "never break user-visible strings" rule or rejecting 
patches with user-visible strings failing to fit 80 chars limit.




-- 
Alexey