linux-kernel - [PATCH v2 6/7] platform/chrome: cros_ec_spi: drop unneeded BUG

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Date:   Fri, 13 May 2022 12:41:42 +0800
From:   Tzung-Bi Shih <tzungbi@...nel.org>
To:     bleung@...omium.org, groeck@...omium.org
Cc:     chrome-platform@...ts.linux.dev, tzungbi@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 6/7] platform/chrome: cros_ec_spi: drop unneeded BUG_ON()

In the context, the following conditions are always false:

- `todo` < 0
Suppose that EC_SPI_FRAME_START is found at the last byte of transfer.

In the case, `ptr` == `end` - 1.  As a result, `todo` must be 0.

- `todo` > `ec_dev->din_size`
Suppose that there is no preamble bytes.  EC_SPI_FRAME_START is found at
the first byte of transfer.

In the case, `end` == `ptr` + EC_MSG_PREAMBLE_COUNT.
As a result, `todo` == EC_MSG_PREAMBLE_COUNT - 1.
However, it already checked `ec_dev->din_size` < EC_MSG_PREAMBLE_COUNT at
the beginning of function.

Drop the unneeded BUG_ON().

Signed-off-by: Tzung-Bi Shih <tzungbi@...nel.org>
---
Changes from v1:
- Separate from the original 6th patch.
- Drop the BUG_ON() instead of returning -EINVAL.

 drivers/platform/chrome/cros_ec_spi.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/platform/chrome/cros_ec_spi.c b/drivers/platform/chrome/cros_ec_spi.c
index 589f18e9537d..5264615f46af 100644
--- a/drivers/platform/chrome/cros_ec_spi.c
+++ b/drivers/platform/chrome/cros_ec_spi.c
@@ -237,7 +237,6 @@ static int cros_ec_spi_receive_packet(struct cros_ec_device *ec_dev,
 	 * start of our buffer
 	 */
 	todo = end - ++ptr;
-	BUG_ON(todo < 0 || todo > ec_dev->din_size);
 	todo = min(todo, need_len);
 	memmove(ec_dev->din, ptr, todo);
 	ptr = ec_dev->din + todo;
@@ -345,7 +344,6 @@ static int cros_ec_spi_receive_response(struct cros_ec_device *ec_dev,
 	 * start of our buffer
 	 */
 	todo = end - ++ptr;
-	BUG_ON(todo < 0 || todo > ec_dev->din_size);
 	todo = min(todo, need_len);
 	memmove(ec_dev->din, ptr, todo);
 	ptr = ec_dev->din + todo;
-- 
2.36.0.550.gb090851708-goog