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

[David Gibson]

On Mon, Jan 18, 2016 at 05:04:55PM +1100, Alexey Kardashevskiy wrote:
> On 01/18/2016 04:35 PM, David Gibson wrote:
> >On Mon, Jan 18, 2016 at 04:17:08PM +1100, Alexey Kardashevskiy wrote:
> >>On 01/18/2016 03:42 PM, David Gibson wrote:
> >>>On Mon, Jan 18, 2016 at 01:44:00PM +1100, Alexey Kardashevskiy wrote:
> >>>>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 <address@hidden>
> >>>>>---
> >>>>>  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.
> >>>
> >>>I'm not.  Or rather, the string is already broken by the PRIu32, so
> >>>the newline doesn't make it any less greppable.
> >>
> >>
> >>"KVM hash page table.*smaller maxmem" stopped working. Not a big deal but I
> >>do not see any win in breaking strings anyway.
> >
> >The problem is that the current pre-commit hooks don't agree with
> >you.  They seem to allow long unbroken strings, but if there's a break
> >like the PRIu32, they won't permit the commit.
> 
> 
> checkpatch.pl reports it as "WARNING: line over 80 characters", not an
> ERROR, so I'd say the hook has a problem.

Well, maybe, but it's not a problem I'm really inclined to tackle at
this time.

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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