[PATCH] cxl: Fix premature commit_end increment on decoder commit failure

[Yuxiong Wang <yuxiong.wang@linux.alibaba.com>]

In cxl_decoder_commit(), commit_end is incremented before verifying whether the
commit succeeded, and the CXL_DECODER_F_ENABLE bit in cxld->flags is only set
after a successful commit. As a result, if the commit fails, commit_end has been
incremented and cxld->reset() has no effect since the flag is not set, so commit_end
remains incorrectly incremented. The inconsistency between commit_end and
CXL_DECODER_F_ENABLE causes failure during subsequent either commit or reset
operations.

Fix this by incrementing commit_end only after confirming the commit succeeded.
Also, remove the ineffective cxld->reset() call. According to CXL 3.2 Spec 8.2.4.20.12
Committing Decoder Programming, since cxld_await_commit() has cleared the decoder
commit bit on failure, no additional reset is required.

Fixes: 176baef ("cxl/hdm: Commit decoder state to hardware")
Signed-off-by: Yuxiong Wang <yuxiong.wang@linux.alibaba.com>
Acked-by: Huang Ying <ying.huang@linux.alibaba.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
---
Change log:
 * Added CXL 3.2 Spec 8.2.4.20.12 Committing Decoder Programming statement. Thanks
   Alison.
 * Collected reviewed-by. Thanks Dave and Alison.
RFC Link: https://lore.kernel.org/linux-cxl/aXqKC-bscufh1ggq@aschofie-mobl2.lan/
---
 drivers/cxl/core/hdm.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
index eb5a3a7640c6..912f648a6b7a 100644
--- a/drivers/cxl/core/hdm.c
+++ b/drivers/cxl/core/hdm.c
@@ -844,14 +844,13 @@ static int cxl_decoder_commit(struct cxl_decoder *cxld)
 	scoped_guard(rwsem_read, &cxl_rwsem.dpa)
 		setup_hw_decoder(cxld, hdm);
 
-	port->commit_end++;
 	rc = cxld_await_commit(hdm, cxld->id);
 	if (rc) {
 		dev_dbg(&port->dev, "%s: error %d committing decoder\n",
 			dev_name(&cxld->dev), rc);
-		cxld->reset(cxld);
 		return rc;
 	}
+	port->commit_end++;
 	cxld->flags |= CXL_DECODER_F_ENABLE;
 
 	return 0;
-- 
2.50.1 (Apple Git-155)