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Subject[PATCH 5/7] habanalabs/gaudi: fix comment to reflect current code
Date
Due to code changes in the past few years, the original comment of
how parser->user_cb_size is checked was not correct anymore.

Fix it to reflect current code and add more explanation as the code
is more complex now.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>
---
drivers/misc/habanalabs/gaudi/gaudi.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/misc/habanalabs/gaudi/gaudi.c b/drivers/misc/habanalabs/gaudi/gaudi.c
index c16c0f9fe202..72b0d145e853 100644
--- a/drivers/misc/habanalabs/gaudi/gaudi.c
+++ b/drivers/misc/habanalabs/gaudi/gaudi.c
@@ -5562,8 +5562,14 @@ static int gaudi_parse_cb_mmu(struct hl_device *hdev,
}

/*
- * The check that parser->user_cb_size <= parser->user_cb->size was done
- * in validate_queue_index().
+ * We are protected from overflow because the check
+ * "parser->user_cb_size <= parser->user_cb->size" was done in get_cb_from_cs_chunk()
+ * in the common code. That check is done only if is_kernel_allocated_cb is true.
+ *
+ * There is no option to reach here without going through that check because:
+ * 1. validate_queue_index() assigns true to is_kernel_allocated_cb for any submission to
+ * an external queue.
+ * 2. For Gaudi, we only parse CBs that were submitted to the external queues.
*/
memcpy(parser->patched_cb->kernel_address,
parser->user_cb->kernel_address,
--
2.25.1
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