Re: [PATCH] ipmi: ssif_bmc: Move smbus_cmd assignment after cleanup

[Quan Nguyen <quan@os.amperecomputing.com>]

On 01/01/2025 23:54, Cosmo Chou wrote:
> Move smbus_cmd assignment to the end of process_smbus_cmd() to ensure
> the new command is not lost when complete_response() is triggered.
> 

Thanks Cosmo for the catch.

And, IMHO, the root cause is the memset() on part buffer called in 
complete_response() is not quite correct. In the current implementation, 
the complete_response() should only be called when the READ is 
completed, ie: only on I2C_SLAVE_STOP of READ transaction, otherwise all 
the info of current on-going request will be mistakenly cleared as in 
this case.

This patch is good and I wonder if we can make this a bit further as below?

diff --git a/drivers/char/ipmi/ssif_bmc.c b/drivers/char/ipmi/ssif_bmc.c
index a14fafc583d4..310f17dd9511 100644
--- a/drivers/char/ipmi/ssif_bmc.c
+++ b/drivers/char/ipmi/ssif_bmc.c
@@ -292,7 +292,6 @@ static void complete_response(struct ssif_bmc_ctx 
*ssif_bmc)
         ssif_bmc->nbytes_processed = 0;
         ssif_bmc->remain_len = 0;
         ssif_bmc->busy = false;
-       memset(&ssif_bmc->part_buf, 0, sizeof(struct ssif_part_buffer));
         wake_up_all(&ssif_bmc->wait_queue);
  }

@@ -744,9 +743,11 @@ static void on_stop_event(struct ssif_bmc_ctx 
*ssif_bmc, u8 *val)
                         ssif_bmc->aborting = true;
                 }
         } else if (ssif_bmc->state == SSIF_RES_SENDING) {
-               if (ssif_bmc->is_singlepart_read || ssif_bmc->block_num 
== 0xFF)
+               if (ssif_bmc->is_singlepart_read || ssif_bmc->block_num 
== 0xFF) {
+                       memset(&ssif_bmc->part_buf, 0, sizeof(struct 
ssif_part_buffer));
                         /* Invalidate response buffer to denote it is 
sent */
                         complete_response(ssif_bmc);
+               }
                 ssif_bmc->state = SSIF_READY;
         }

Thanks and Happy New Year.
- Quan