2024-02-26 19:03:46

by Daniel Golle

Subject: [PATCH] mtd: ubi: fix NVMEM over UBI volumes on 32-bit systems

A compiler warning related to sizeof(int) != 8 when calling do_div()
is triggered when building on 32-bit platforms.
Address this by using integer types having a well-defined size where
appropriate.

Fixes: 3ce485803da1 ("mtd: ubi: provide NVMEM layer over UBI volumes")
Signed-off-by: Daniel Golle <[email protected]>
---
drivers/mtd/ubi/nvmem.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/ubi/nvmem.c b/drivers/mtd/ubi/nvmem.c
index b7a93c495d172..5820a170d2512 100644
--- a/drivers/mtd/ubi/nvmem.c
+++ b/drivers/mtd/ubi/nvmem.c
@@ -23,14 +23,17 @@ struct ubi_nvmem {
static int ubi_nvmem_reg_read(void *priv, unsigned int from,
void *val, size_t bytes)
{
- int err = 0, lnum = from, offs, bytes_left = bytes, to_read;
+ uint32_t bytes_left, offs, to_read;
struct ubi_nvmem *unv = priv;
struct ubi_volume_desc *desc;
+ uint64_t lnum = from;
+ int err = 0;

desc = ubi_open_volume(unv->ubi_num, unv->vol_id, UBI_READONLY);
if (IS_ERR(desc))
return PTR_ERR(desc);

+ bytes_left = bytes;
offs = do_div(lnum, unv->usable_leb_size);
while (bytes_left) {
to_read = unv->usable_leb_size - offs;
--
2.44.0

2024-02-27 02:24:05

by Zhihao Cheng

Subject: Re: [PATCH] mtd: ubi: fix NVMEM over UBI volumes on 32-bit systems

?? 2024/2/27 2:23, Daniel Golle д??:
> A compiler warning related to sizeof(int) != 8 when calling do_div()
> is triggered when building on 32-bit platforms.
> Address this by using integer types having a well-defined size where
> appropriate.
>
> Fixes: 3ce485803da1 ("mtd: ubi: provide NVMEM layer over UBI volumes")
> Signed-off-by: Daniel Golle <[email protected]>
> ---
> drivers/mtd/ubi/nvmem.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mtd/ubi/nvmem.c b/drivers/mtd/ubi/nvmem.c
> index b7a93c495d172..5820a170d2512 100644
> --- a/drivers/mtd/ubi/nvmem.c
> +++ b/drivers/mtd/ubi/nvmem.c
> @@ -23,14 +23,17 @@ struct ubi_nvmem {
> static int ubi_nvmem_reg_read(void *priv, unsigned int from,
> void *val, size_t bytes)
> {
> - int err = 0, lnum = from, offs, bytes_left = bytes, to_read;
> + uint32_t bytes_left, offs, to_read;
> struct ubi_nvmem *unv = priv;
> struct ubi_volume_desc *desc;
> + uint64_t lnum = from;
> + int err = 0;
>
> desc = ubi_open_volume(unv->ubi_num, unv->vol_id, UBI_READONLY);
> if (IS_ERR(desc))
> return PTR_ERR(desc);
>
> + bytes_left = bytes;
The 'bytes' is a size_t type, which has 64 bits on 64-bit platforms.
This assignment will lead a type truncation, so should we add a explicit
type conversion here to avoid compiler warning?
> offs = do_div(lnum, unv->usable_leb_size);
> while (bytes_left) {
> to_read = unv->usable_leb_size - offs;
>

2024-02-27 12:58:03

by Daniel Golle

Subject: Re: [PATCH] mtd: ubi: fix NVMEM over UBI volumes on 32-bit systems

On Tue, Feb 27, 2024 at 10:23:17AM +0800, Zhihao Cheng wrote:
> 在 2024/2/27 2:23, Daniel Golle 写道:
> > A compiler warning related to sizeof(int) != 8 when calling do_div()
> > is triggered when building on 32-bit platforms.
> > Address this by using integer types having a well-defined size where
> > appropriate.
> >
> > Fixes: 3ce485803da1 ("mtd: ubi: provide NVMEM layer over UBI volumes")
> > Signed-off-by: Daniel Golle <[email protected]>
> > ---
> > drivers/mtd/ubi/nvmem.c | 5 ++++-
> > 1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/mtd/ubi/nvmem.c b/drivers/mtd/ubi/nvmem.c
> > index b7a93c495d172..5820a170d2512 100644
> > --- a/drivers/mtd/ubi/nvmem.c
> > +++ b/drivers/mtd/ubi/nvmem.c
> > @@ -23,14 +23,17 @@ struct ubi_nvmem {
> > static int ubi_nvmem_reg_read(void *priv, unsigned int from,
> > void *val, size_t bytes)
> > {
> > - int err = 0, lnum = from, offs, bytes_left = bytes, to_read;
> > + uint32_t bytes_left, offs, to_read;
> > struct ubi_nvmem *unv = priv;
> > struct ubi_volume_desc *desc;
> > + uint64_t lnum = from;
> > + int err = 0;
> > desc = ubi_open_volume(unv->ubi_num, unv->vol_id, UBI_READONLY);
> > if (IS_ERR(desc))
> > return PTR_ERR(desc);
> > + bytes_left = bytes;
> The 'bytes' is a size_t type, which has 64 bits on 64-bit platforms. This
> assignment will lead a type truncation, so should we add a explicit type
> conversion here to avoid compiler warning?

Oh right. I reckon the best is to declare 'bytes' as 'size_t' type as well
then. I will send v2 with that change shortly.


> > offs = do_div(lnum, unv->usable_leb_size);
> > while (bytes_left) {
> > to_read = unv->usable_leb_size - offs;
> >
>
>
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