linux-kernel - [PATCH 5.14 345/432] mmc: core: Avoid hogging the CPU while polling for busy for mmc ioctls

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Message-Id: <20210916155822.522528425@linuxfoundation.org>
Date:   Thu, 16 Sep 2021 18:01:34 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Ulf Hansson <ulf.hansson@...aro.org>,
        Shawn Lin <shawn.lin@...k-chips.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.14 345/432] mmc: core: Avoid hogging the CPU while polling for busy for mmc ioctls

From: Ulf Hansson <ulf.hansson@...aro.org>

[ Upstream commit 468108155b0f89cc08189cc33f9bacfe9da8a125 ]

When __mmc_blk_ioctl_cmd() calls card_busy_detect() to verify that the
card's states moves back into transfer state, the polling with CMD13 is
done without any delays in between the commands being sent.

Rather than fixing card_busy_detect() in this regards, let's instead
convert into using the common mmc_poll_for_busy(), which also helps us to
avoid open-coding.

Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
Reviewed-by: Shawn Lin <shawn.lin@...k-chips.com>
Link: https://lore.kernel.org/r/20210702134229.357717-3-ulf.hansson@linaro.org
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/mmc/core/block.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
index 170343411f53..c30d0ab15539 100644
--- a/drivers/mmc/core/block.c
+++ b/drivers/mmc/core/block.c
@@ -605,7 +605,8 @@ static int __mmc_blk_ioctl_cmd(struct mmc_card *card, struct mmc_blk_data *md,
 		 * Ensure RPMB/R1B command has completed by polling CMD13
 		 * "Send Status".
 		 */
-		err = card_busy_detect(card, MMC_BLK_TIMEOUT_MS, NULL);
+		err = mmc_poll_for_busy(card, MMC_BLK_TIMEOUT_MS, false,
+					MMC_BUSY_IO);
 	}
 
 	return err;
-- 
2.30.2