2020-04-15 14:41:16

by Scott Branden

Subject: [PATCH] test_firmware: remove unnecessary test_fw_mutex in test_dev_config_show_xxx

Remove unnecessary use of test_fw_mutex in test_dev_config_show_xxx
functions that show simple bool, int, and u8.

Signed-off-by: Scott Branden <[email protected]>
---
lib/test_firmware.c | 26 +++-----------------------
1 file changed, 3 insertions(+), 23 deletions(-)

diff --git a/lib/test_firmware.c b/lib/test_firmware.c
index 0c7fbcf07ac5..9fee2b93a8d1 100644
--- a/lib/test_firmware.c
+++ b/lib/test_firmware.c
@@ -310,27 +310,13 @@ static int test_dev_config_update_bool(const char *buf, size_t size,
return ret;
}

-static ssize_t
-test_dev_config_show_bool(char *buf,
- bool config)
+static ssize_t test_dev_config_show_bool(char *buf, bool val)
{
- bool val;
-
- mutex_lock(&test_fw_mutex);
- val = config;
- mutex_unlock(&test_fw_mutex);
-
return snprintf(buf, PAGE_SIZE, "%d\n", val);
}

-static ssize_t test_dev_config_show_int(char *buf, int cfg)
+static ssize_t test_dev_config_show_int(char *buf, int val)
{
- int val;
-
- mutex_lock(&test_fw_mutex);
- val = cfg;
- mutex_unlock(&test_fw_mutex);
-
return snprintf(buf, PAGE_SIZE, "%d\n", val);
}

@@ -354,14 +340,8 @@ static int test_dev_config_update_u8(const char *buf, size_t size, u8 *cfg)
return size;
}

-static ssize_t test_dev_config_show_u8(char *buf, u8 cfg)
+static ssize_t test_dev_config_show_u8(char *buf, u8 val)
{
- u8 val;
-
- mutex_lock(&test_fw_mutex);
- val = cfg;
- mutex_unlock(&test_fw_mutex);
-
return snprintf(buf, PAGE_SIZE, "%u\n", val);
}

--
2.17.1

2020-04-15 22:04:12

by Kees Cook

Subject: Re: [PATCH] test_firmware: remove unnecessary test_fw_mutex in test_dev_config_show_xxx

On Tue, Apr 14, 2020 at 05:25:17PM -0700, Scott Branden wrote:
> Remove unnecessary use of test_fw_mutex in test_dev_config_show_xxx
> functions that show simple bool, int, and u8.

I would expect at least a READ_ONCE(), yes?

>
> Signed-off-by: Scott Branden <[email protected]>
> ---
> lib/test_firmware.c | 26 +++-----------------------
> 1 file changed, 3 insertions(+), 23 deletions(-)
>
> diff --git a/lib/test_firmware.c b/lib/test_firmware.c
> index 0c7fbcf07ac5..9fee2b93a8d1 100644
> --- a/lib/test_firmware.c
> +++ b/lib/test_firmware.c
> @@ -310,27 +310,13 @@ static int test_dev_config_update_bool(const char *buf, size_t size,
> return ret;
> }
>
> -static ssize_t
> -test_dev_config_show_bool(char *buf,
> - bool config)
> +static ssize_t test_dev_config_show_bool(char *buf, bool val)
> {
> - bool val;
> -
> - mutex_lock(&test_fw_mutex);
> - val = config;
> - mutex_unlock(&test_fw_mutex);
> -
> return snprintf(buf, PAGE_SIZE, "%d\n", val);
> }
>
> -static ssize_t test_dev_config_show_int(char *buf, int cfg)
> +static ssize_t test_dev_config_show_int(char *buf, int val)
> {
> - int val;
> -
> - mutex_lock(&test_fw_mutex);
> - val = cfg;
> - mutex_unlock(&test_fw_mutex);
> -
> return snprintf(buf, PAGE_SIZE, "%d\n", val);
> }
>
> @@ -354,14 +340,8 @@ static int test_dev_config_update_u8(const char *buf, size_t size, u8 *cfg)
> return size;
> }
>
> -static ssize_t test_dev_config_show_u8(char *buf, u8 cfg)
> +static ssize_t test_dev_config_show_u8(char *buf, u8 val)
> {
> - u8 val;
> -
> - mutex_lock(&test_fw_mutex);
> - val = cfg;
> - mutex_unlock(&test_fw_mutex);
> -
> return snprintf(buf, PAGE_SIZE, "%u\n", val);
> }
>
> --
> 2.17.1
>

--
Kees Cook

2020-04-16 00:21:28

by Scott Branden

Subject: Re: [PATCH] test_firmware: remove unnecessary test_fw_mutex in test_dev_config_show_xxx

Hi Kees,

On 2020-04-14 8:10 p.m., Kees Cook wrote:
> On Tue, Apr 14, 2020 at 05:25:17PM -0700, Scott Branden wrote:
>> Remove unnecessary use of test_fw_mutex in test_dev_config_show_xxx
>> functions that show simple bool, int, and u8.
> I would expect at least a READ_ONCE(), yes?
I don't understand why you need a READ_ONCE when removing a mutex around
an assignment
of a parameter passed into a function being assigned to a local variable.

Could you please explain your expectations.
>
>> Signed-off-by: Scott Branden <[email protected]>
>> ---
>> lib/test_firmware.c | 26 +++-----------------------
>> 1 file changed, 3 insertions(+), 23 deletions(-)
>>
>> diff --git a/lib/test_firmware.c b/lib/test_firmware.c
>> index 0c7fbcf07ac5..9fee2b93a8d1 100644
>> --- a/lib/test_firmware.c
>> +++ b/lib/test_firmware.c
>> @@ -310,27 +310,13 @@ static int test_dev_config_update_bool(const char *buf, size_t size,
>> return ret;
>> }
>>
>> -static ssize_t
>> -test_dev_config_show_bool(char *buf,
>> - bool config)
>> +static ssize_t test_dev_config_show_bool(char *buf, bool val)
>> {
>> - bool val;
>> -
>> - mutex_lock(&test_fw_mutex);
>> - val = config;
>> - mutex_unlock(&test_fw_mutex);
>> -
>> return snprintf(buf, PAGE_SIZE, "%d\n", val);
>> }
>>
>> -static ssize_t test_dev_config_show_int(char *buf, int cfg)
>> +static ssize_t test_dev_config_show_int(char *buf, int val)
>> {
>> - int val;
>> -
>> - mutex_lock(&test_fw_mutex);
>> - val = cfg;
>> - mutex_unlock(&test_fw_mutex);
>> -
>> return snprintf(buf, PAGE_SIZE, "%d\n", val);
>> }
>>
>> @@ -354,14 +340,8 @@ static int test_dev_config_update_u8(const char *buf, size_t size, u8 *cfg)
>> return size;
>> }
>>
>> -static ssize_t test_dev_config_show_u8(char *buf, u8 cfg)
>> +static ssize_t test_dev_config_show_u8(char *buf, u8 val)
>> {
>> - u8 val;
>> -
>> - mutex_lock(&test_fw_mutex);
>> - val = cfg;
>> - mutex_unlock(&test_fw_mutex);
>> -
>> return snprintf(buf, PAGE_SIZE, "%u\n", val);
>> }
>>
>> --
>> 2.17.1
>>

2020-04-16 00:22:11

by Kees Cook

Subject: Re: [PATCH] test_firmware: remove unnecessary test_fw_mutex in test_dev_config_show_xxx

On Wed, Apr 15, 2020 at 09:28:18AM -0700, Scott Branden wrote:
> Hi Kees,
>
> On 2020-04-14 8:10 p.m., Kees Cook wrote:
> > On Tue, Apr 14, 2020 at 05:25:17PM -0700, Scott Branden wrote:
> > > Remove unnecessary use of test_fw_mutex in test_dev_config_show_xxx
> > > functions that show simple bool, int, and u8.
> > I would expect at least a READ_ONCE(), yes?
> I don't understand why you need a READ_ONCE when removing a mutex around an
> assignment
> of a parameter passed into a function being assigned to a local variable.
>
> Could you please explain your expectations.

Oops, yes, you're right. I misread and was thinking this was reading
from a global. This looks fine.

Reviewed-by: Kees Cook <[email protected]>

-Kees

> >
> > > Signed-off-by: Scott Branden <[email protected]>
> > > ---
> > > lib/test_firmware.c | 26 +++-----------------------
> > > 1 file changed, 3 insertions(+), 23 deletions(-)
> > >
> > > diff --git a/lib/test_firmware.c b/lib/test_firmware.c
> > > index 0c7fbcf07ac5..9fee2b93a8d1 100644
> > > --- a/lib/test_firmware.c
> > > +++ b/lib/test_firmware.c
> > > @@ -310,27 +310,13 @@ static int test_dev_config_update_bool(const char *buf, size_t size,
> > > return ret;
> > > }
> > > -static ssize_t
> > > -test_dev_config_show_bool(char *buf,
> > > - bool config)
> > > +static ssize_t test_dev_config_show_bool(char *buf, bool val)
> > > {
> > > - bool val;
> > > -
> > > - mutex_lock(&test_fw_mutex);
> > > - val = config;
> > > - mutex_unlock(&test_fw_mutex);
> > > -
> > > return snprintf(buf, PAGE_SIZE, "%d\n", val);
> > > }
> > > -static ssize_t test_dev_config_show_int(char *buf, int cfg)
> > > +static ssize_t test_dev_config_show_int(char *buf, int val)
> > > {
> > > - int val;
> > > -
> > > - mutex_lock(&test_fw_mutex);
> > > - val = cfg;
> > > - mutex_unlock(&test_fw_mutex);
> > > -
> > > return snprintf(buf, PAGE_SIZE, "%d\n", val);
> > > }
> > > @@ -354,14 +340,8 @@ static int test_dev_config_update_u8(const char *buf, size_t size, u8 *cfg)
> > > return size;
> > > }
> > > -static ssize_t test_dev_config_show_u8(char *buf, u8 cfg)
> > > +static ssize_t test_dev_config_show_u8(char *buf, u8 val)
> > > {
> > > - u8 val;
> > > -
> > > - mutex_lock(&test_fw_mutex);
> > > - val = cfg;
> > > - mutex_unlock(&test_fw_mutex);
> > > -
> > > return snprintf(buf, PAGE_SIZE, "%u\n", val);
> > > }
> > > --
> > > 2.17.1
> > >
>

--
Kees Cook

2020-04-16 06:02:22

by Luis Chamberlain

Subject: Re: [PATCH] test_firmware: remove unnecessary test_fw_mutex in test_dev_config_show_xxx

On Wed, Apr 15, 2020 at 09:44:31AM -0700, Kees Cook wrote:
> On Wed, Apr 15, 2020 at 09:28:18AM -0700, Scott Branden wrote:
> > Hi Kees,
> >
> > On 2020-04-14 8:10 p.m., Kees Cook wrote:
> > > On Tue, Apr 14, 2020 at 05:25:17PM -0700, Scott Branden wrote:
> > > > Remove unnecessary use of test_fw_mutex in test_dev_config_show_xxx
> > > > functions that show simple bool, int, and u8.
> > > I would expect at least a READ_ONCE(), yes?
> > I don't understand why you need a READ_ONCE when removing a mutex around an
> > assignment
> > of a parameter passed into a function being assigned to a local variable.
> >
> > Could you please explain your expectations.
>
> Oops, yes, you're right. I misread and was thinking this was reading
> from a global. This looks fine.
>
> Reviewed-by: Kees Cook <[email protected]>

Reviewed-by: Luis Chamberlain <[email protected]>

Luis