diff mbox series

[RFC,05/11] drivers/acpi: convert seqno counter_atomic

Message ID 9e2c6cccabc96fe1e5304e2fa2dfdad28ca5ac9c.1600816121.git.skhan@linuxfoundation.org
State Superseded
Headers show
Series None | expand

Commit Message

Shuah Khan Sept. 23, 2020, 1:43 a.m. UTC
counter_atomic is introduced to be used when a variable is used as
a simple counter and doesn't guard object lifetimes. This clearly
differentiates atomic_t usages that guard object lifetimes.

counter_atomic variables will wrap around to 0 when it overflows and
should not be used to guard resource lifetimes, device usage and
open counts that control state changes, and pm states.

seqno is a sequence number counter for logging. This counter gets
incremented. Unsure if there is a chance of this overflowing. It
doesn't look like overflowing causes any problems since it is used
to tag the log messages and nothing more.

Convert it to use counter_atomic.

This conversion doesn't change the oveflow wrap around behavior.

Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
---
 drivers/acpi/acpi_extlog.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Comments

Rafael J. Wysocki Sept. 24, 2020, 11:13 a.m. UTC | #1
On Wed, Sep 23, 2020 at 3:44 AM Shuah Khan <skhan@linuxfoundation.org> wrote:
>
> counter_atomic is introduced to be used when a variable is used as
> a simple counter and doesn't guard object lifetimes. This clearly
> differentiates atomic_t usages that guard object lifetimes.
>
> counter_atomic variables will wrap around to 0 when it overflows and
> should not be used to guard resource lifetimes, device usage and
> open counts that control state changes, and pm states.
>
> seqno is a sequence number counter for logging. This counter gets
> incremented. Unsure if there is a chance of this overflowing. It
> doesn't look like overflowing causes any problems since it is used
> to tag the log messages and nothing more.
>
> Convert it to use counter_atomic.
>
> This conversion doesn't change the oveflow wrap around behavior.
>
> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

Both this change and the next patch are fine by me.

Thanks!

> ---
>  drivers/acpi/acpi_extlog.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/acpi/acpi_extlog.c b/drivers/acpi/acpi_extlog.c
> index f138e12b7b82..23b696b7eb14 100644
> --- a/drivers/acpi/acpi_extlog.c
> +++ b/drivers/acpi/acpi_extlog.c
> @@ -12,6 +12,7 @@
>  #include <linux/ratelimit.h>
>  #include <linux/edac.h>
>  #include <linux/ras.h>
> +#include <linux/counters.h>
>  #include <asm/cpu.h>
>  #include <asm/mce.h>
>
> @@ -93,7 +94,7 @@ static struct acpi_hest_generic_status *extlog_elog_entry_check(int cpu, int ban
>  static void __print_extlog_rcd(const char *pfx,
>                                struct acpi_hest_generic_status *estatus, int cpu)
>  {
> -       static atomic_t seqno;
> +       static struct counter_atomic seqno;
>         unsigned int curr_seqno;
>         char pfx_seq[64];
>
> @@ -103,7 +104,7 @@ static void __print_extlog_rcd(const char *pfx,
>                 else
>                         pfx = KERN_ERR;
>         }
> -       curr_seqno = atomic_inc_return(&seqno);
> +       curr_seqno = counter_atomic_inc_return(&seqno);
>         snprintf(pfx_seq, sizeof(pfx_seq), "%s{%u}", pfx, curr_seqno);
>         printk("%s""Hardware error detected on CPU%d\n", pfx_seq, cpu);
>         cper_estatus_print(pfx_seq, estatus);
> --
> 2.25.1
>
Shuah Khan Sept. 24, 2020, 3:08 p.m. UTC | #2
On 9/24/20 5:13 AM, Rafael J. Wysocki wrote:
> On Wed, Sep 23, 2020 at 3:44 AM Shuah Khan <skhan@linuxfoundation.org> wrote:
>>
>> counter_atomic is introduced to be used when a variable is used as
>> a simple counter and doesn't guard object lifetimes. This clearly
>> differentiates atomic_t usages that guard object lifetimes.
>>
>> counter_atomic variables will wrap around to 0 when it overflows and
>> should not be used to guard resource lifetimes, device usage and
>> open counts that control state changes, and pm states.
>>
>> seqno is a sequence number counter for logging. This counter gets
>> incremented. Unsure if there is a chance of this overflowing. It
>> doesn't look like overflowing causes any problems since it is used
>> to tag the log messages and nothing more.
>>
>> Convert it to use counter_atomic.
>>
>> This conversion doesn't change the oveflow wrap around behavior.

I see typo here. Will fix it.

>>
>> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
> 
> Both this change and the next patch are fine by me.
> 

Thanks Rafael. Okay to add your Acked-by?

thanks,
-- Shuah
Rafael J. Wysocki Sept. 24, 2020, 3:32 p.m. UTC | #3
On Thu, Sep 24, 2020 at 5:08 PM Shuah Khan <skhan@linuxfoundation.org> wrote:
>

> On 9/24/20 5:13 AM, Rafael J. Wysocki wrote:

> > On Wed, Sep 23, 2020 at 3:44 AM Shuah Khan <skhan@linuxfoundation.org> wrote:

> >>

> >> counter_atomic is introduced to be used when a variable is used as

> >> a simple counter and doesn't guard object lifetimes. This clearly

> >> differentiates atomic_t usages that guard object lifetimes.

> >>

> >> counter_atomic variables will wrap around to 0 when it overflows and

> >> should not be used to guard resource lifetimes, device usage and

> >> open counts that control state changes, and pm states.

> >>

> >> seqno is a sequence number counter for logging. This counter gets

> >> incremented. Unsure if there is a chance of this overflowing. It

> >> doesn't look like overflowing causes any problems since it is used

> >> to tag the log messages and nothing more.

> >>

> >> Convert it to use counter_atomic.

> >>

> >> This conversion doesn't change the oveflow wrap around behavior.

>

> I see typo here. Will fix it.

>

> >>

> >> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

> >

> > Both this change and the next patch are fine by me.

> >

>

> Thanks Rafael. Okay to add your Acked-by?


Sure.

Thanks!
diff mbox series

Patch

diff --git a/drivers/acpi/acpi_extlog.c b/drivers/acpi/acpi_extlog.c
index f138e12b7b82..23b696b7eb14 100644
--- a/drivers/acpi/acpi_extlog.c
+++ b/drivers/acpi/acpi_extlog.c
@@ -12,6 +12,7 @@ 
 #include <linux/ratelimit.h>
 #include <linux/edac.h>
 #include <linux/ras.h>
+#include <linux/counters.h>
 #include <asm/cpu.h>
 #include <asm/mce.h>
 
@@ -93,7 +94,7 @@  static struct acpi_hest_generic_status *extlog_elog_entry_check(int cpu, int ban
 static void __print_extlog_rcd(const char *pfx,
 			       struct acpi_hest_generic_status *estatus, int cpu)
 {
-	static atomic_t seqno;
+	static struct counter_atomic seqno;
 	unsigned int curr_seqno;
 	char pfx_seq[64];
 
@@ -103,7 +104,7 @@  static void __print_extlog_rcd(const char *pfx,
 		else
 			pfx = KERN_ERR;
 	}
-	curr_seqno = atomic_inc_return(&seqno);
+	curr_seqno = counter_atomic_inc_return(&seqno);
 	snprintf(pfx_seq, sizeof(pfx_seq), "%s{%u}", pfx, curr_seqno);
 	printk("%s""Hardware error detected on CPU%d\n", pfx_seq, cpu);
 	cper_estatus_print(pfx_seq, estatus);