Messages in this thread Patch in this message | | | Date | Thu, 1 Dec 2022 07:30:30 -0800 | From | Ira Weiny <> | Subject | Re: [PATCH V2 03/11] cxl/mem: Implement Clear Event Records command |
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On Thu, Dec 01, 2022 at 01:26:18PM +0000, Jonathan Cameron wrote: > On Wed, 30 Nov 2022 16:27:11 -0800 > ira.weiny@intel.com wrote: > > > From: Ira Weiny <ira.weiny@intel.com> > > > > CXL rev 3.0 section 8.2.9.2.3 defines the Clear Event Records mailbox > > command. After an event record is read it needs to be cleared from the > > event log. > > > > Implement cxl_clear_event_record() to clear all record retrieved from > > the device. > > > > Each record is cleared explicitly. A clear all bit is specified but > > events could arrive between a get and any final clear all operation. > > This means events would be missed. > > Therefore each event is cleared specifically. > > > > Signed-off-by: Ira Weiny <ira.weiny@intel.com> > I think there is a type issue on the min_t() calculation with that addressed > this looks good to me. > > Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> > > > > > --- > > Changes from V1: > > Clear Event Record allows for u8 handles while Get Event Record > > allows for u16 records to be returned. Based on Jonathan's > > feedback; allow for all event records to be handled in this > > clear. Which means a double loop with potentially multiple > > Clear Event payloads being sent to clear all events sent. > > > > Changes from RFC: > > Jonathan > > Clean up init of payload and use return code. > > Also report any error to clear the event. > > s/v3.0/rev 3.0 > > --- > > drivers/cxl/core/mbox.c | 61 +++++++++++++++++++++++++++++++----- > > drivers/cxl/cxlmem.h | 14 +++++++++ > > include/uapi/linux/cxl_mem.h | 1 + > > 3 files changed, 69 insertions(+), 7 deletions(-) > > > > diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c > > index 70b681027a3d..076a3df0ba38 100644 > > --- a/drivers/cxl/core/mbox.c > > +++ b/drivers/cxl/core/mbox.c > > @@ -52,6 +52,7 @@ static struct cxl_mem_command cxl_mem_commands[CXL_MEM_COMMAND_ID_MAX] = { > > #endif > > CXL_CMD(GET_SUPPORTED_LOGS, 0, CXL_VARIABLE_PAYLOAD, CXL_CMD_FLAG_FORCE_ENABLE), > > CXL_CMD(GET_EVENT_RECORD, 1, CXL_VARIABLE_PAYLOAD, 0), > > + CXL_CMD(CLEAR_EVENT_RECORD, CXL_VARIABLE_PAYLOAD, 0, 0), > > CXL_CMD(GET_FW_INFO, 0, 0x50, 0), > > CXL_CMD(GET_PARTITION_INFO, 0, 0x20, 0), > > CXL_CMD(GET_LSA, 0x8, CXL_VARIABLE_PAYLOAD, 0), > > @@ -708,6 +709,42 @@ int cxl_enumerate_cmds(struct cxl_dev_state *cxlds) > > } > > EXPORT_SYMBOL_NS_GPL(cxl_enumerate_cmds, CXL); > > > > +static int cxl_clear_event_record(struct cxl_dev_state *cxlds, > > + enum cxl_event_log_type log, > > + struct cxl_get_event_payload *get_pl, > > + u16 total) > > +{ > > + struct cxl_mbox_clear_event_payload payload = { > > + .event_log = log, > > + }; > > + int cnt; > > + > > + /* > > + * Clear Event Records uses u8 for the handle cnt while Get Event > > + * Record can return up to 0xffff records. > > + */ > > + for (cnt = 0; cnt < total; /* cnt incremented internally */) { > > + u8 nr_recs = min_t(u8, (total - cnt), > > + CXL_CLEAR_EVENT_MAX_HANDLES); > > I might be half asleep but isn't this assuming that (total - cnt) > fits in an u8? Shouldn't this be min_t(u16, ..)
This cast will ensure the value is never out of range for nr_recs which needs to be u8 and (total - cnt) will never be negative.
But now you have me double thinking myself.
> Also, maybe u16 cnt would be simpler. > > Hmm. This is safe but only because of how you call it alongside > handling of a particular Get event records response (which must > have fitted in the mailbox and has a longer header). > > Looking at this function in isolation, I think the mailbox could be > small enough that we might not fit 255 records + the header. > Perhaps we need a comment to say that, or at minimum a check and error > return if it won't fit?
I did not realize that Payload Size applied to input payloads as well. :-/ There is no check in the send command for that ATM. Looking at the spec I think you are right.
I'll further limit the payload size here too.
And with this I might get rid of the min_t() and just cap based on that value. > > > + int i, rc; > > + > > + for (i = 0; i < nr_recs; i++, cnt++) { > > + payload.handle[i] = get_pl->records[cnt].hdr.handle; > > + dev_dbg(cxlds->dev, "Event log '%s': Clearning %u\n", > > + cxl_event_log_type_str(log), > > + le16_to_cpu(payload.handle[i])); > > + } > > + payload.nr_recs = nr_recs; > > + > > + rc = cxl_mbox_send_cmd(cxlds, CXL_MBOX_OP_CLEAR_EVENT_RECORD, > > + &payload, sizeof(payload), NULL, 0); > > + if (rc) > > + return rc; > > + } > > + > > + return 0; > > +} > > + > > static void cxl_mem_get_records_log(struct cxl_dev_state *cxlds, > > enum cxl_event_log_type type) > > { > > @@ -732,13 +769,22 @@ static void cxl_mem_get_records_log(struct cxl_dev_state *cxlds, > This feels miss named now but I can't immediately think of better naming so on that > basis fine to leave it as is if you don't have a better idea!.
So we leave it. Naming is hard! :-D
Thanks for the quick review, V3 coming ASAP. Ira
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