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SubjectRe: Re: [PATCH] mmc: host: use kzalloc instead of kmalloc and memset
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On Tue, 17 Dec 2019, 15:33 Greg KH <gregkh@linuxfoundation.org> wrote:
>> Signed-off-by: Pan Zhang <zhangpan26@huawei.com>
>> ---
>> drivers/mmc/host/vub300.c | 4 +---
>> 1 file changed, 1 insertion(+), 3 deletions(-)

>I know I can not take patches without any changelog text, hopefully other maintainers also do the same.

>Please fix,

and

>> Signed-off-by: Pan Zhang <zhangpan26@huawei.com>
>> ---
>> drivers/mmc/host/vub300.c | 12 ++++--------
>> 1 file changed, 4 insertions(+), 8 deletions(-)

>What changed from v1? Always put that below the --- line.

I am so sorry about that I didnot explain this patch clearly.
I complemented patch v2 just after sending the patch v1 because I found that following code has similar problems.

My changelog text can be also my reply to the following question:

On Tue, 17 Dec 2019, 15:32 David Rientjes <rientjes@google.com> wrote:
>I think the previous code is an optimization since the first interrupt_size bytes
>or ts bytes of xfer_buffer would otherwise unnecessarily be zeroed and then copied to.

Part of the memory will be written twice after this change, but that
should be negligible.
1. xfer_buffer or xfer_buffer - interrupt_size, it won't be big.
2. __download_offload_pseudocode func wouldnot be called frequently.


Signed-off-by: Pan Zhang <zhangpan26@huawei.com>
---
drivers/mmc/host/vub300.c | 12 ++++--------
1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/mmc/host/vub300.c b/drivers/mmc/host/vub300.c
index 6ced1b7..e18931d 100644
--- a/drivers/mmc/host/vub300.c
+++ b/drivers/mmc/host/vub300.c
@@ -1227,12 +1227,10 @@ static void __download_offload_pseudocode(struct vub300_mmc_host *vub300,
size -= 1;
if (interrupt_size < size) {
u16 xfer_length = roundup_to_multiple_of_64(interrupt_size);
- u8 *xfer_buffer = kmalloc(xfer_length, GFP_KERNEL);
+ u8 *xfer_buffer = kzalloc(xfer_length, GFP_KERNEL);
if (xfer_buffer) {
int retval;
memcpy(xfer_buffer, data, interrupt_size);
- memset(xfer_buffer + interrupt_size, 0,
- xfer_length - interrupt_size);
size -= interrupt_size;
data += interrupt_size;
retval =
@@ -1270,12 +1268,10 @@ static void __download_offload_pseudocode(struct vub300_mmc_host *vub300,
size -= 1;
if (ts < size) {
u16 xfer_length = roundup_to_multiple_of_64(ts);
- u8 *xfer_buffer = kmalloc(xfer_length, GFP_KERNEL);
+ u8 *xfer_buffer = kzalloc(xfer_length, GFP_KERNEL);
if (xfer_buffer) {
int retval;
memcpy(xfer_buffer, data, ts);
- memset(xfer_buffer + ts, 0,
- xfer_length - ts);
size -= ts;
data += ts;
retval =
@@ -1465,7 +1461,7 @@ static int __command_read_data(struct vub300_mmc_host *vub300,
}
}
} else {
- u8 *buf = kmalloc(padded_length, GFP_KERNEL);
+ u8 *buf = kzalloc(padded_length, GFP_KERNEL);
if (buf) {
int result;
unsigned pipe = usb_rcvbulkpipe(vub300->udev,
@@ -2024,7 +2020,7 @@ static void vub300_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
msleep(600);
vub300->card_powered = 1;
} else if (ios->power_mode == MMC_POWER_ON) {
- u8 *buf = kmalloc(8, GFP_KERNEL);
+ u8 *buf = kzalloc(8, GFP_KERNEL);
if (buf) {
__set_clock_speed(vub300, buf, ios);
kfree(buf);
--
2.7.4
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