From:   "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
To:     outreachy@lists.linux.dev,
        Khadija Kamran <kamrankhadijadj@gmail.com>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5] staging: axis-fifo: initialize timeouts in probe only
Date:   Thu, 16 Mar 2023 15:38:03 +0100
Message-ID: <2626731.BddDVKsqQX@suse>
In-Reply-To: <ZBMR4s8xyHGqMm72@khadija-virtual-machine>
References: <ZBMR4s8xyHGqMm72@khadija-virtual-machine>
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Precedence: bulk

Khadija,

Just saw your v5 patch and Greg's two replies.

=46or v6 you will need to change the subject to "[PATCH v6] staging: axis-f=
ifo:=20
initialize timeouts in init only" to indicate that you are doing assignment=
s=20
in axis_fifo_init().

Don't forget to extend the version log with "Changes in v6:" and clarify th=
at=20
v5 had a different "Object" (you should probably also add a link to the v5=
=20
patch in lore: https://lore.kernel.org/lkml /ZBMR4s8xyHGqMm72@khadija-virtu=
al-
machine/). When the "Subject" changes, readers may not find the previous=20
versions easily.   =20

On gioved=EC 16 marzo 2023 13:56:02 CET Khadija Kamran wrote:
> Module parameter, read_timeout, can only be set at the loading time. As
> it can only be modified once, initialize read_timeout once in the probe

Substitute "probe" with "init".

> function.
>=20
> As a result, only use read_timeout as the last argument in
> wait_event_interruptible_timeout() call.

This two sentences are not much clear. I'd merge and rework:

"Initialize the module parameters read_timeout and write_timeout once in=20
init().

Module parameters can only be set once and cannot be modified later, so we=
=20
don't need to evaluate them again when passing the parameters to =20
wait_event_interruptible_timeout()."  =20

>=20
> Convert datatpe

s/datatpe/type/

> of read_timeout

of {read,write}_timeout

> from 'int' to 'long int' because
> implicit conversion of 'long int' to 'int' in statement 'read_timeout =3D
> MAX_SCHEDULE_TIMEOUT' results in an overflow warning.

We don't care too much about the warning themselves: I mean, it overflows a=
nd=20
you must avoid it to happen (as you are doing with the changes of types), n=
ot=20
merely be interested in avoiding the warning. "[] results in an overflow." =
is=20
all we care about.

Add also the previous paragraph in the last part of the commit message.
=20
> Perform same steps formodule parameter, write_timeout.

And instead delete the this last phrase.

> Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Signed-off-by: Khadija Kamran <kamrankhadijadj@gmail.com>
> ---
>=20
> Changes in v5:
>  - Convert timeout's datatype from int to long.
> Changes in v4:
>  - Initialize timeouts once as suggested by Greg; this automatically
>    fixes the indentation problems.
>  - Change the subject and description.
> Changes in v3:
>  - Fix grammatical mistakes
>  - Do not change the second argument's indentation in split lines
> Changes in v2:
>  - Instead of matching alignment to open parenthesis, align second and
>    the last argument instead.
>  - Change the subject to 'remove tabs to align arguments'.
>  - Use imperative language in subject and description
>=20
>  drivers/staging/axis-fifo/axis-fifo.c | 26 ++++++++++++++++----------
>  1 file changed, 16 insertions(+), 10 deletions(-)
>=20
> diff --git a/drivers/staging/axis-fifo/axis-fifo.c
> b/drivers/staging/axis-fifo/axis-fifo.c index dfd2b357f484..d667dc80df47
> 100644
> --- a/drivers/staging/axis-fifo/axis-fifo.c
> +++ b/drivers/staging/axis-fifo/axis-fifo.c
> @@ -103,17 +103,17 @@
>   *           globals
>   * ----------------------------
>   */
> -static int read_timeout =3D 1000; /* ms to wait before read() times out =
*/
> -static int write_timeout =3D 1000; /* ms to wait before write() times ou=
t */
> +static long read_timeout =3D 1000; /* ms to wait before read() times out=
 */
> +static long write_timeout =3D 1000; /* ms to wait before write() times o=
ut */
>=20
>  /* ----------------------------
>   * module command-line arguments
>   * ----------------------------
>   */
>=20
> -module_param(read_timeout, int, 0444);
> +module_param(read_timeout, long, 0444);
>  MODULE_PARM_DESC(read_timeout, "ms to wait before blocking read() timing=
=20
out;
> set to -1 for no timeout"); -module_param(write_timeout, int, 0444);
> +module_param(write_timeout, long, 0444);
>  MODULE_PARM_DESC(write_timeout, "ms to wait before blocking write() timi=
ng
> out; set to -1 for no timeout");
>=20
>  /* ----------------------------
> @@ -384,9 +384,7 @@ static ssize_t axis_fifo_read(struct file *f, char=20
__user
> *buf, mutex_lock(&fifo->read_lock);
>  		ret =3D wait_event_interruptible_timeout(fifo->read_queue,
>  			ioread32(fifo->base_addr + XLLF_RDFO_OFFSET),
> -				 (read_timeout >=3D 0) ?
> -				  msecs_to_jiffies(read_timeout) :
> -				  MAX_SCHEDULE_TIMEOUT);
> +			read_timeout);
>=20
>  		if (ret <=3D 0) {
>  			if (ret =3D=3D 0) {
> @@ -528,9 +526,7 @@ static ssize_t axis_fifo_write(struct file *f, const=
=20
char
> __user *buf, ret =3D wait_event_interruptible_timeout(fifo->write_queue,
>  			ioread32(fifo->base_addr + XLLF_TDFV_OFFSET)
>=20
>  				 >=3D words_to_write,

What is this? You haven't yet compiled your patch.
Any further problems with enabling axis-fifo as a module?

=46abio

>=20
> -				 (write_timeout >=3D 0) ?
> -				  msecs_to_jiffies(write_timeout) :
> -				  MAX_SCHEDULE_TIMEOUT);
> +			write_timeout);
>=20
>  		if (ret <=3D 0) {
>  			if (ret =3D=3D 0) {
> @@ -815,6 +811,16 @@ static int axis_fifo_probe(struct platform_device=20
*pdev)
>  	char *device_name;
>  	int rc =3D 0; /* error return value */
>=20
> +	if (read_timeout >=3D 0)
> +		read_timeout =3D msecs_to_jiffies(read_timeout);
> +	else
> +		read_timeout =3D MAX_SCHEDULE_TIMEOUT;
> +
> +	if (write_timeout >=3D 0)
> +		write_timeout =3D msecs_to_jiffies(write_timeout);
> +	else
> +		write_timeout =3D MAX_SCHEDULE_TIMEOUT;
> +
>  	/* ----------------------------
>  	 *     init wrapper device
>  	 * ----------------------------
> --
> 2.34.1