[PATCH] mmc: core: sd: Remove unused buffer allocation in sd_enable_cache()

[PATCH] mmc: core: sd: Remove unused buffer allocation in sd_enable_cache()

[Chanwoo Lee]

sd_enable_cache() allocates a 512-byte buffer that is never used.
sd_write_ext_reg() allocates its own internal buffer, and no read-back
verification is done in this function. Remove the unnecessary allocation.

Fixes: 130206a615a9 ("mmc: core: Add support for cache ctrl for SD cards")
Signed-off-by: Chanwoo Lee <cw9316.lee@samsung.com>
---
 drivers/mmc/core/sd.c | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index 948948ca9b4a..c763efb10f64 100644
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -1379,15 +1379,10 @@ static int sd_flush_cache(struct mmc_host *host)
 
 static int sd_enable_cache(struct mmc_card *card)
 {
-	u8 *reg_buf;
 	int err;
 
 	card->ext_perf.feature_enabled &= ~SD_EXT_PERF_CACHE;
 
-	reg_buf = kzalloc(512, GFP_KERNEL);
-	if (!reg_buf)
-		return -ENOMEM;
-
 	/*
 	 * Set Cache Enable at bit 0 in the performance enhancement register at
 	 * 260 bytes offset.
@@ -1397,7 +1392,7 @@ static int sd_enable_cache(struct mmc_card *card)
 	if (err) {
 		pr_warn("%s: error %d writing Cache Enable bit\n",
 			mmc_hostname(card->host), err);
-		goto out;
+		return err;
 	}
 
 	err = mmc_poll_for_busy(card, SD_WRITE_EXTR_SINGLE_TIMEOUT_MS, false,
@@ -1405,8 +1400,6 @@ static int sd_enable_cache(struct mmc_card *card)
 	if (!err)
 		card->ext_perf.feature_enabled |= SD_EXT_PERF_CACHE;
 
-out:
-	kfree(reg_buf);
 	return err;
 }
 
-- 
2.43.0

RE: [PATCH] mmc: core: sd: Remove unused buffer allocation in sd_enable_cache()

[Avri Altman]

> sd_enable_cache() allocates a 512-byte buffer that is never used.
> sd_write_ext_reg() allocates its own internal buffer, and no read-back verification
> is done in this function. Remove the unnecessary allocation.
> 
> Fixes: 130206a615a9 ("mmc: core: Add support for cache ctrl for SD cards")
> Signed-off-by: Chanwoo Lee <cw9316.lee@samsung.com>
Reviewed-by: Avri Altman <avri.altman@sandisk.com>

Re: [PATCH] mmc: core: sd: Remove unused buffer allocation in sd_enable_cache()

[Shawn Lin]

在 2026/06/02 星期二 17:40, Chanwoo Lee 写道:
> sd_enable_cache() allocates a 512-byte buffer that is never used.
> sd_write_ext_reg() allocates its own internal buffer, and no read-back
> verification is done in this function. Remove the unnecessary allocation.
> 
> Fixes: 130206a615a9 ("mmc: core: Add support for cache ctrl for SD cards")

This cleanup doesn't deserve a fixes tag, otherwise

Reviewed-by: Shawn Lin <shawn.lin@linux.dev>

> Signed-off-by: Chanwoo Lee <cw9316.lee@samsung.com>
> ---
>   drivers/mmc/core/sd.c | 9 +--------
>   1 file changed, 1 insertion(+), 8 deletions(-)
> 
> diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
> index 948948ca9b4a..c763efb10f64 100644
> --- a/drivers/mmc/core/sd.c
> +++ b/drivers/mmc/core/sd.c
> @@ -1379,15 +1379,10 @@ static int sd_flush_cache(struct mmc_host *host)
>   
>   static int sd_enable_cache(struct mmc_card *card)
>   {
> -	u8 *reg_buf;
>   	int err;
>   
>   	card->ext_perf.feature_enabled &= ~SD_EXT_PERF_CACHE;
>   
> -	reg_buf = kzalloc(512, GFP_KERNEL);
> -	if (!reg_buf)
> -		return -ENOMEM;
> -
>   	/*
>   	 * Set Cache Enable at bit 0 in the performance enhancement register at
>   	 * 260 bytes offset.
> @@ -1397,7 +1392,7 @@ static int sd_enable_cache(struct mmc_card *card)
>   	if (err) {
>   		pr_warn("%s: error %d writing Cache Enable bit\n",
>   			mmc_hostname(card->host), err);
> -		goto out;
> +		return err;
>   	}
>   
>   	err = mmc_poll_for_busy(card, SD_WRITE_EXTR_SINGLE_TIMEOUT_MS, false,
> @@ -1405,8 +1400,6 @@ static int sd_enable_cache(struct mmc_card *card)
>   	if (!err)
>   		card->ext_perf.feature_enabled |= SD_EXT_PERF_CACHE;
>   
> -out:
> -	kfree(reg_buf);
>   	return err;
>   }
>