When copying memory from one buffer to another, instead of open-coding
loops with byte-by-byte copies let's use memcpy() which might be a bit
faster and makes intent more clear.
Signed-off-by: Dmitry Torokhov <[email protected]>
---
Changes in v3:
- new patch using memcpy() for moving data around
drivers/i2c/i2c-core-smbus.c | 15 +++++----------
1 file changed, 5 insertions(+), 10 deletions(-)
diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c
index 7b4e2270eeda1..bbafdd3b1b114 100644
--- a/drivers/i2c/i2c-core-smbus.c
+++ b/drivers/i2c/i2c-core-smbus.c
@@ -397,8 +397,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
}
i2c_smbus_try_get_dmabuf(&msg[0], command);
- for (i = 1; i < msg[0].len; i++)
- msg[0].buf[i] = data->block[i - 1];
+ memcpy(msg[0].buf + 1, data->block, msg[0].len - 1);
}
break;
case I2C_SMBUS_BLOCK_PROC_CALL:
@@ -413,8 +412,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
msg[0].len = data->block[0] + 2;
i2c_smbus_try_get_dmabuf(&msg[0], command);
- for (i = 1; i < msg[0].len; i++)
- msg[0].buf[i] = data->block[i - 1];
+ memcpy(msg[0].buf + 1, data->block, msg[0].len - 1);
msg[1].flags |= I2C_M_RECV_LEN;
msg[1].len = 1; /* block length will be added by
@@ -436,8 +434,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
msg[0].len = data->block[0] + 1;
i2c_smbus_try_get_dmabuf(&msg[0], command);
- for (i = 1; i <= data->block[0]; i++)
- msg[0].buf[i] = data->block[i];
+ memcpy(msg[0].buf + 1, data->block + 1, data->block[0]);
}
break;
default:
@@ -489,13 +486,11 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
data->word = get_unaligned_le16(msgbuf1);
break;
case I2C_SMBUS_I2C_BLOCK_DATA:
- for (i = 0; i < data->block[0]; i++)
- data->block[i + 1] = msg[1].buf[i];
+ memcpy(data->block + 1, msg[1].buf, data->block[0]);
break;
case I2C_SMBUS_BLOCK_DATA:
case I2C_SMBUS_BLOCK_PROC_CALL:
- for (i = 0; i < msg[1].buf[0] + 1; i++)
- data->block[i] = msg[1].buf[i];
+ memcpy(data->block, msg[1].buf, msg[1].buf[0] + 1);
break;
}
--
2.24.0.rc1.363.gb1bccd3e3d-goog
Hi Dmitry,
On 12/11/19 21:31, Dmitry Torokhov wrote:
> When copying memory from one buffer to another, instead of open-coding
> loops with byte-by-byte copies let's use memcpy() which might be a bit
> faster and makes intent more clear.
Good idea!
Reviewed-by: Luca Ceresoli <[email protected]>
--
Luca
Hello Dmitry,
On Tue, Nov 12, 2019 at 12:31:32PM -0800, Dmitry Torokhov wrote:
> When copying memory from one buffer to another, instead of open-coding
> loops with byte-by-byte copies let's use memcpy() which might be a bit
> faster and makes intent more clear.
>
> Signed-off-by: Dmitry Torokhov <[email protected]>
>
> ---
>
> Changes in v3:
> - new patch using memcpy() for moving data around
>
> drivers/i2c/i2c-core-smbus.c | 15 +++++----------
> 1 file changed, 5 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c
> index 7b4e2270eeda1..bbafdd3b1b114 100644
> --- a/drivers/i2c/i2c-core-smbus.c
> +++ b/drivers/i2c/i2c-core-smbus.c
> @@ -397,8 +397,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
> }
>
> i2c_smbus_try_get_dmabuf(&msg[0], command);
> - for (i = 1; i < msg[0].len; i++)
> - msg[0].buf[i] = data->block[i - 1];
> + memcpy(msg[0].buf + 1, data->block, msg[0].len - 1);
Can it happen that msg[0].len is zero?
> }
> break;
> case I2C_SMBUS_BLOCK_PROC_CALL:
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-K?nig |
Industrial Linux Solutions | https://www.pengutronix.de/ |
On Mon, Nov 18, 2019 at 08:47:57AM +0100, Uwe Kleine-K?nig wrote:
> Hello Dmitry,
>
> On Tue, Nov 12, 2019 at 12:31:32PM -0800, Dmitry Torokhov wrote:
> > When copying memory from one buffer to another, instead of open-coding
> > loops with byte-by-byte copies let's use memcpy() which might be a bit
> > faster and makes intent more clear.
> >
> > Signed-off-by: Dmitry Torokhov <[email protected]>
> >
> > ---
> >
> > Changes in v3:
> > - new patch using memcpy() for moving data around
> >
> > drivers/i2c/i2c-core-smbus.c | 15 +++++----------
> > 1 file changed, 5 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c
> > index 7b4e2270eeda1..bbafdd3b1b114 100644
> > --- a/drivers/i2c/i2c-core-smbus.c
> > +++ b/drivers/i2c/i2c-core-smbus.c
> > @@ -397,8 +397,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
> > }
> >
> > i2c_smbus_try_get_dmabuf(&msg[0], command);
> > - for (i = 1; i < msg[0].len; i++)
> > - msg[0].buf[i] = data->block[i - 1];
> > + memcpy(msg[0].buf + 1, data->block, msg[0].len - 1);
>
> Can it happen that msg[0].len is zero?
No, it can not, because of the "msg[0].len = data->block[0] + 2;" line
above.
Thanks.
--
Dmitry
On Mon, Nov 18, 2019 at 12:09:39AM -0800, Dmitry Torokhov wrote:
> On Mon, Nov 18, 2019 at 08:47:57AM +0100, Uwe Kleine-K?nig wrote:
> > Hello Dmitry,
> >
> > On Tue, Nov 12, 2019 at 12:31:32PM -0800, Dmitry Torokhov wrote:
> > > When copying memory from one buffer to another, instead of open-coding
> > > loops with byte-by-byte copies let's use memcpy() which might be a bit
> > > faster and makes intent more clear.
> > >
> > > Signed-off-by: Dmitry Torokhov <[email protected]>
> > >
> > > ---
> > >
> > > Changes in v3:
> > > - new patch using memcpy() for moving data around
> > >
> > > drivers/i2c/i2c-core-smbus.c | 15 +++++----------
> > > 1 file changed, 5 insertions(+), 10 deletions(-)
> > >
> > > diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c
> > > index 7b4e2270eeda1..bbafdd3b1b114 100644
> > > --- a/drivers/i2c/i2c-core-smbus.c
> > > +++ b/drivers/i2c/i2c-core-smbus.c
> > > @@ -397,8 +397,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
> > > }
> > >
> > > i2c_smbus_try_get_dmabuf(&msg[0], command);
> > > - for (i = 1; i < msg[0].len; i++)
> > > - msg[0].buf[i] = data->block[i - 1];
> > > + memcpy(msg[0].buf + 1, data->block, msg[0].len - 1);
> >
> > Can it happen that msg[0].len is zero?
>
> No, it can not, because of the "msg[0].len = data->block[0] + 2;" line
> above.
OK, and as passing data with data->block[0] = 254 also makes the code do
strange things already without your patch. I now also checked the other
conversions for similar problems and didn't find any. So:
Acked-by: Uwe Kleine-K?nig <[email protected]>
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-K?nig |
Industrial Linux Solutions | https://www.pengutronix.de/ |
On Tue, Nov 12, 2019 at 12:31:32PM -0800, Dmitry Torokhov wrote:
> When copying memory from one buffer to another, instead of open-coding
> loops with byte-by-byte copies let's use memcpy() which might be a bit
> faster and makes intent more clear.
>
> Signed-off-by: Dmitry Torokhov <[email protected]>
>
This one I like very much! Applied to for-next, thanks!