* [PATCH] block: drop dead assignments in loop_init()
@ 2020-12-11 18:12 Lukas Bulwahn
2020-12-11 18:23 ` Julia Lawall
0 siblings, 1 reply; 4+ messages in thread
From: Lukas Bulwahn @ 2020-12-11 18:12 UTC (permalink / raw)
To: Christoph Hellwig, Jens Axboe, linux-block
Cc: Hannes Reinecke, linux-kernel, clang-built-linux,
kernel-janitors, Lukas Bulwahn
Commit 8410d38c2552 ("loop: use __register_blkdev to allocate devices on
demand") simplified loop_init(); so computing the range of the block region
is not required anymore and can be dropped.
Drop dead assignments in loop_init().
As compilers will detect these unneeded assignments and optimize this,
the resulting object code is identical before and after this change.
No functional change. No change in object code.
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
---
Christoph, please ack.
Jens, please pick this minor non-urgent clean-up patch on your
block -next tree on top of Christoph's commit above.
drivers/block/loop.c | 3 ---
1 file changed, 3 deletions(-)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index d2ce1ddc192d..eed4bc5ef5c5 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -2304,7 +2304,6 @@ MODULE_ALIAS("devname:loop-control");
static int __init loop_init(void)
{
int i, nr;
- unsigned long range;
struct loop_device *lo;
int err;
@@ -2343,10 +2342,8 @@ static int __init loop_init(void)
*/
if (max_loop) {
nr = max_loop;
- range = max_loop << part_shift;
} else {
nr = CONFIG_BLK_DEV_LOOP_MIN_COUNT;
- range = 1UL << MINORBITS;
}
err = misc_register(&loop_misc);
--
2.17.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] block: drop dead assignments in loop_init()
2020-12-11 18:12 [PATCH] block: drop dead assignments in loop_init() Lukas Bulwahn
@ 2020-12-11 18:23 ` Julia Lawall
2020-12-11 18:40 ` Lukas Bulwahn
0 siblings, 1 reply; 4+ messages in thread
From: Julia Lawall @ 2020-12-11 18:23 UTC (permalink / raw)
To: Lukas Bulwahn
Cc: Christoph Hellwig, Jens Axboe, linux-block, Hannes Reinecke,
linux-kernel, clang-built-linux, kernel-janitors
On Fri, 11 Dec 2020, Lukas Bulwahn wrote:
> Commit 8410d38c2552 ("loop: use __register_blkdev to allocate devices on
> demand") simplified loop_init(); so computing the range of the block region
> is not required anymore and can be dropped.
>
> Drop dead assignments in loop_init().
>
> As compilers will detect these unneeded assignments and optimize this,
> the resulting object code is identical before and after this change.
>
> No functional change. No change in object code.
It looks like some braces should be dropped too?
julia
>
> Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
> ---
> Christoph, please ack.
>
> Jens, please pick this minor non-urgent clean-up patch on your
> block -next tree on top of Christoph's commit above.
>
> drivers/block/loop.c | 3 ---
> 1 file changed, 3 deletions(-)
>
> diff --git a/drivers/block/loop.c b/drivers/block/loop.c
> index d2ce1ddc192d..eed4bc5ef5c5 100644
> --- a/drivers/block/loop.c
> +++ b/drivers/block/loop.c
> @@ -2304,7 +2304,6 @@ MODULE_ALIAS("devname:loop-control");
> static int __init loop_init(void)
> {
> int i, nr;
> - unsigned long range;
> struct loop_device *lo;
> int err;
>
> @@ -2343,10 +2342,8 @@ static int __init loop_init(void)
> */
> if (max_loop) {
> nr = max_loop;
> - range = max_loop << part_shift;
> } else {
> nr = CONFIG_BLK_DEV_LOOP_MIN_COUNT;
> - range = 1UL << MINORBITS;
> }
>
> err = misc_register(&loop_misc);
> --
> 2.17.1
>
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] block: drop dead assignments in loop_init()
2020-12-11 18:23 ` Julia Lawall
@ 2020-12-11 18:40 ` Lukas Bulwahn
2020-12-12 4:27 ` Joe Perches
0 siblings, 1 reply; 4+ messages in thread
From: Lukas Bulwahn @ 2020-12-11 18:40 UTC (permalink / raw)
To: Julia Lawall
Cc: Christoph Hellwig, Jens Axboe, linux-block, Hannes Reinecke,
Linux Kernel Mailing List, clang-built-linux, kernel-janitors
On Fri, Dec 11, 2020 at 7:23 PM Julia Lawall <julia.lawall@inria.fr> wrote:
>
>
>
> On Fri, 11 Dec 2020, Lukas Bulwahn wrote:
>
> > Commit 8410d38c2552 ("loop: use __register_blkdev to allocate devices on
> > demand") simplified loop_init(); so computing the range of the block region
> > is not required anymore and can be dropped.
> >
> > Drop dead assignments in loop_init().
> >
> > As compilers will detect these unneeded assignments and optimize this,
> > the resulting object code is identical before and after this change.
> >
> > No functional change. No change in object code.
>
> It looks like some braces should be dropped too?
>
> julia
>
Julia, you are right; I just rewrote it to:
nr = max_loop ? max_loop : CONFIG_BLK_DEV_LOOP_MIN_COUNT;
v2 will follow in a moment.
Lukas
> >
> > Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
> > ---
> > Christoph, please ack.
> >
> > Jens, please pick this minor non-urgent clean-up patch on your
> > block -next tree on top of Christoph's commit above.
> >
> > drivers/block/loop.c | 3 ---
> > 1 file changed, 3 deletions(-)
> >
> > diff --git a/drivers/block/loop.c b/drivers/block/loop.c
> > index d2ce1ddc192d..eed4bc5ef5c5 100644
> > --- a/drivers/block/loop.c
> > +++ b/drivers/block/loop.c
> > @@ -2304,7 +2304,6 @@ MODULE_ALIAS("devname:loop-control");
> > static int __init loop_init(void)
> > {
> > int i, nr;
> > - unsigned long range;
> > struct loop_device *lo;
> > int err;
> >
> > @@ -2343,10 +2342,8 @@ static int __init loop_init(void)
> > */
> > if (max_loop) {
> > nr = max_loop;
> > - range = max_loop << part_shift;
> > } else {
> > nr = CONFIG_BLK_DEV_LOOP_MIN_COUNT;
> > - range = 1UL << MINORBITS;
> > }
> >
> > err = misc_register(&loop_misc);
> > --
> > 2.17.1
> >
> >
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] block: drop dead assignments in loop_init()
2020-12-11 18:40 ` Lukas Bulwahn
@ 2020-12-12 4:27 ` Joe Perches
0 siblings, 0 replies; 4+ messages in thread
From: Joe Perches @ 2020-12-12 4:27 UTC (permalink / raw)
To: Lukas Bulwahn, Julia Lawall
Cc: Christoph Hellwig, Jens Axboe, linux-block, Hannes Reinecke,
Linux Kernel Mailing List, clang-built-linux, kernel-janitors
On Fri, 2020-12-11 at 19:40 +0100, Lukas Bulwahn wrote:
> On Fri, Dec 11, 2020 at 7:23 PM Julia Lawall <julia.lawall@inria.fr> wrote:
> > On Fri, 11 Dec 2020, Lukas Bulwahn wrote:
> > > Commit 8410d38c2552 ("loop: use __register_blkdev to allocate devices on
> > > demand") simplified loop_init(); so computing the range of the block region
> > > is not required anymore and can be dropped.
> > >
> > > Drop dead assignments in loop_init().
> > >
> > > As compilers will detect these unneeded assignments and optimize this,
> > > the resulting object code is identical before and after this change.
> > >
> > > No functional change. No change in object code.
> >
> > It looks like some braces should be dropped too?
> I just rewrote it to:
>
> nr = max_loop ? max_loop : CONFIG_BLK_DEV_LOOP_MIN_COUNT;
A relatively common gcc extension would use ?: like:
nr = max_loop ?: CONFIG_BLK_DEV_LOOP_MIN_COUNT;
^ permalink raw reply [flat|nested] 4+ messages in thread
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2020-12-11 18:12 [PATCH] block: drop dead assignments in loop_init() Lukas Bulwahn
2020-12-11 18:23 ` Julia Lawall
2020-12-11 18:40 ` Lukas Bulwahn
2020-12-12 4:27 ` Joe Perches
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