On 2018/10/9 15:00, Michael Ellerman wrote: > YueHaibing <yuehaib...@huawei.com> writes: >> 'aa_index' is defined as an unsigned value, but find_aa_index >> may return -1 when dlpar_clone_property fails. So we use an rc >> value to track the validation of finding the aa_index instead >> of the 'aa_index' value itself >> >> Fixes: c05a5a40969e ("powerpc/pseries: Dynamic add entires to associativity >> lookup array") >> Signed-off-by: YueHaibing <yuehaib...@huawei.com> >> --- >> v2: use 'rc' track the validation of aa_index > > Thanks for sending a v2, some more comments ... > >> diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c >> b/arch/powerpc/platforms/pseries/hotplug-memory.c >> index 9a15d39..796e68b 100644 >> --- a/arch/powerpc/platforms/pseries/hotplug-memory.c >> +++ b/arch/powerpc/platforms/pseries/hotplug-memory.c >> @@ -101,13 +101,12 @@ static struct property *dlpar_clone_property(struct >> property *prop, >> return new_prop; >> } >> >> -static u32 find_aa_index(struct device_node *dr_node, >> - struct property *ala_prop, const u32 *lmb_assoc) >> +static int find_aa_index(struct device_node *dr_node, struct property >> *ala_prop, >> + const u32 *lmb_assoc, u32 *aa_index) >> { >> u32 *assoc_arrays; >> - u32 aa_index; >> int aa_arrays, aa_array_entries, aa_array_sz; >> - int i, index; >> + int i, index, rc = -1; > > It's preferable to leave rc uninitialised until we actually need to > initialise it, that gives the compiler the chance to warn us if we use > it inadvertently before that. > >> >> /* >> * The ibm,associativity-lookup-arrays property is defined to be >> @@ -121,18 +120,18 @@ static u32 find_aa_index(struct device_node *dr_node, >> aa_array_entries = be32_to_cpu(assoc_arrays[1]); >> aa_array_sz = aa_array_entries * sizeof(u32); >> >> - aa_index = -1; > > So that would be here: > rc = -1; > > But .. > >> for (i = 0; i < aa_arrays; i++) { >> index = (i * aa_array_entries) + 2; >> >> if (memcmp(&assoc_arrays[index], &lmb_assoc[1], aa_array_sz)) >> continue; >> >> - aa_index = i; >> + *aa_index = i; >> + rc = 0; >> break; >> } > > The 'rc' variable is basically a boolean now, it means "we found something". > > And all we do with it in the found case (rc = 0) is test it below and return. > > So can't we just return directly in the for loop above, rather than breaking? > > In which case we don't need the rc variable at all. > > And the whole function may as well return bool, rather than int. > > Does that make sense?
Yes, will do that in v3. > > cheers > >> - if (aa_index == -1) { >> + if (rc == -1) { >> struct property *new_prop; >> u32 new_prop_size; >> >> @@ -157,10 +156,11 @@ static u32 find_aa_index(struct device_node *dr_node, >> * number of entries - 1 since we added its associativity >> * to the end of the lookup array. >> */ >> - aa_index = be32_to_cpu(assoc_arrays[0]) - 1; >> + *aa_index = be32_to_cpu(assoc_arrays[0]) - 1; >> + rc = 0; >> } >> >> - return aa_index; >> + return rc; >> } >> >> static int update_lmb_associativity_index(struct drmem_lmb *lmb) > > . >