A truncated response, caused by host power-off, or other conditions,
can lead to message desynchronization.
Raw trace data (STOP loss scenario, add state transition comment):
1. T-1: Read response phase (SSIF_RES_SENDING)
8271.955342 WR_RCV [03] <- Read polling cmd
8271.955348 RD_REQ [04] <== SSIF_RES_SENDING <- start sending response
8271.955436 RD_PRO [b4]
8271.955527 RD_PRO [00]
8271.955618 RD_PRO [c1]
8271.955707 RD_PRO [00]
8271.955814 RD_PRO [ad] <== SSIF_RES_SENDING <- last byte
<- !! STOP lost (truncated response)
2. T: New Write request arrives, BMC still in SSIF_RES_SENDING
8271.967973 WR_REQ [] <== SSIF_RES_SENDING >> SSIF_ABORTING <- log:
unexpected WR_REQ in RES_SENDING
8271.968447 WR_RCV [02] <== SSIF_ABORTING <- do nothing
8271.968452 WR_RCV [02] <== SSIF_ABORTING <- do nothing
8271.968454 WR_RCV [18] <== SSIF_ABORTING <- do nothing
8271.968456 WR_RCV [01] <== SSIF_ABORTING <- do nothing
8271.968458 WR_RCV [66] <== SSIF_ABORTING <- do nothing
8271.978714 STOP [] <== SSIF_ABORTING >> SSIF_READY <- log: unexpected
SLAVE STOP in state=SSIF_ABORTING
3. T+1: Next Read polling, treated as a fresh transaction
8271.979125 WR_REQ [] <== SSIF_READY >> SSIF_START
8271.979326 WR_RCV [03] <== SSIF_START >> SSIF_SMBUS_CMD <-
smbus_cmd=0x03
8271.979331 RD_REQ [04] <== SSIF_RES_SENDING <- sending response
8271.979427 RD_PRO [b4] <- !! this is T's stale
response -> desynchronization
When in SSIF_ABORTING state, a newly arrived command should still be
handled to avoid dropping the request or causing message
desynchronization.
Fixes: dd2bc5cc9e25 ("ipmi: ssif_bmc: Add SSIF BMC driver")
Signed-off-by: Jian Zhang <[email protected]>
---
drivers/char/ipmi/ssif_bmc.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/drivers/char/ipmi/ssif_bmc.c b/drivers/char/ipmi/ssif_bmc.c
index fbc7d2cfd535..a1e1a7f1e104 100644
--- a/drivers/char/ipmi/ssif_bmc.c
+++ b/drivers/char/ipmi/ssif_bmc.c
@@ -458,6 +458,15 @@ static bool supported_write_cmd(u8 cmd)
return false;
}
+static bool supported_write_start_cmd(u8 cmd)
+{
+ if (cmd == SSIF_IPMI_SINGLEPART_WRITE ||
+ cmd == SSIF_IPMI_MULTIPART_WRITE_START)
+ return true;
+
+ return false;
+}
+
/* Process the IPMI response that will be read by master */
static void handle_read_processed(struct ssif_bmc_ctx *ssif_bmc, u8 *val)
{
@@ -709,6 +718,11 @@ static void on_write_received_event(struct ssif_bmc_ctx
*ssif_bmc, u8 *val)
ssif_bmc->state = SSIF_ABORTING;
else
ssif_bmc->state = SSIF_REQ_RECVING;
+ } else if (ssif_bmc->state == SSIF_ABORTING) {
+ if (supported_write_start_cmd(*val)) {
+ ssif_bmc->state = SSIF_SMBUS_CMD;
+ ssif_bmc->aborting = false;
+ }
}
/* This is response sending state */
--
2.20.1
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