Messages in this thread | | | Date | Mon, 12 Aug 2019 11:32:48 +0100 | From | Sudeep Holla <> | Subject | Re: [PATCH] firmware: arm_scmi: Eliminate local db variable in SCMI_PERF_FC_RING_DB |
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On Fri, Aug 09, 2019 at 09:49:10PM -0700, Nathan Chancellor wrote: > clang warns four times: > > drivers/firmware/arm_scmi/perf.c:320:24: warning: variable 'db' is > uninitialized when used within its own initialization [-Wuninitialized] > SCMI_PERF_FC_RING_DB(db, 64); > ~~~~~~~~~~~~~~~~~~~~~^~~~~~~ > drivers/firmware/arm_scmi/perf.c:300:31: note: expanded from macro > 'SCMI_PERF_FC_RING_DB' > struct scmi_fc_db_info *db = doorbell; \ > ~~ ^~~~~~~~ > > This happens because the doorbell identifier becomes db after > preprocessing: > > if (db->width == 1) > do { > u8 val = 0; > struct scmi_fc_db_info *db = db; > if (db->mask) > val = ioread8(db->addr) & db->mask; > iowrite8((u8)db->set | val, db->addr); > } while (0); > > We could swap the doorbell and db identifiers within the macro and that > would resolve the issue; however, there doesn't appear to be a good > reason for having two copies of the same variable. Eliminate the one in > the do while loop to prevent this warning and make the code clearer. >
I originally had exactly what we will after this patch applied. I think one of the tool complained about argument 'db' reused in the macro might have possible side-effects. That's the reason I moved it. I will dig it up and fold this in the original patch as before.
-- Regards, Sudeep
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