Re: [PATCH 09/11] drivers/char/ipmi: convert stats to use counter_atomic32

Corey Minyard
2020-09-26T00:15:16Z

On Fri, Sep 25, 2020 at 05:47:23PM -0600, Shuah Khan 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.
>
> atomic_t variables used for stats are atomic counters. Overflow will
> wrap around and reset the stats and no change with the conversion.
>
> Convert them to use counter_atomic32.
>
> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

Reviewed-by: Corey Minyard <cminyard@mvista.com>

I assume for this conversion that the plan is to eliminate atomic_t
completely and convert all atomic counters used for object lifetime to
struct kref? The new naming is certainly more clear and I'm happy with
this change.

-corey

> ---
> drivers/char/ipmi/ipmi_msghandler.c | 9 +++++----
> drivers/char/ipmi/ipmi_si_intf.c | 9 +++++----
> 2 files changed, 10 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
> index 737c0b6b24ea..36c0b1be22fb 100644
> --- a/drivers/char/ipmi/ipmi_msghandler.c
> +++ b/drivers/char/ipmi/ipmi_msghandler.c
> @@ -34,6 +34,7 @@
> #include <linux/uuid.h>
> #include <linux/nospec.h>
> #include <linux/vmalloc.h>
> +#include <linux/counters.h>
>
> #define IPMI_DRIVER_VERSION "39.2"
>
> @@ -584,7 +585,7 @@ struct ipmi_smi {
> struct ipmi_my_addrinfo addrinfo[IPMI_MAX_CHANNELS];
> bool channels_ready;
>
> - atomic_t stats[IPMI_NUM_STATS];
> + struct counter_atomic32 stats[IPMI_NUM_STATS];
>
> /*
> * run_to_completion duplicate of smb_info, smi_info
> @@ -630,9 +631,9 @@ static LIST_HEAD(smi_watchers);
> static DEFINE_MUTEX(smi_watchers_mutex);
>
> #define ipmi_inc_stat(intf, stat) \
> - atomic_inc(&(intf)->stats[IPMI_STAT_ ## stat])
> + counter_atomic32_inc(&(intf)->stats[IPMI_STAT_ ## stat])
> #define ipmi_get_stat(intf, stat) \
> - ((unsigned int) atomic_read(&(intf)->stats[IPMI_STAT_ ## stat]))
> + ((unsigned int) counter_atomic32_read(&(intf)->stats[IPMI_STAT_ ## stat]))
>
> static const char * const addr_src_to_str[] = {
> "invalid", "hotmod", "hardcoded", "SPMI", "ACPI", "SMBIOS", "PCI",
> @@ -3448,7 +3449,7 @@ int ipmi_add_smi(struct module *owner,
> INIT_LIST_HEAD(&intf->cmd_rcvrs);
> init_waitqueue_head(&intf->waitq);
> for (i = 0; i < IPMI_NUM_STATS; i++)
> - atomic_set(&intf->stats[i], 0);
> + counter_atomic32_set(&intf->stats[i], 0);
>
> mutex_lock(&ipmi_interfaces_mutex);
> /* Look for a hole in the numbers. */
> diff --git a/drivers/char/ipmi/ipmi_si_intf.c b/drivers/char/ipmi/ipmi_si_intf.c
> index 77b8d551ae7f..0909a3461f05 100644
> --- a/drivers/char/ipmi/ipmi_si_intf.c
> +++ b/drivers/char/ipmi/ipmi_si_intf.c
> @@ -43,6 +43,7 @@
> #include "ipmi_si_sm.h"
> #include <linux/string.h>
> #include <linux/ctype.h>
> +#include <linux/counters.h>
>
> /* Measure times between events in the driver. */
> #undef DEBUG_TIMING
> @@ -237,7 +238,7 @@ struct smi_info {
> bool dev_group_added;
>
> /* Counters and things for the proc filesystem. */
> - atomic_t stats[SI_NUM_STATS];
> + struct counter_atomic32 stats[SI_NUM_STATS];
>
> struct task_struct *thread;
>
> @@ -245,9 +246,9 @@ struct smi_info {
> };
>
> #define smi_inc_stat(smi, stat) \
> - atomic_inc(&(smi)->stats[SI_STAT_ ## stat])
> + counter_atomic32_inc(&(smi)->stats[SI_STAT_ ## stat])
> #define smi_get_stat(smi, stat) \
> - ((unsigned int) atomic_read(&(smi)->stats[SI_STAT_ ## stat]))
> + ((unsigned int) counter_atomic32_read(&(smi)->stats[SI_STAT_ ## stat]))
>
> #define IPMI_MAX_INTFS 4
> static int force_kipmid[IPMI_MAX_INTFS];
> @@ -2013,7 +2014,7 @@ static int try_smi_init(struct smi_info *new_smi)
> atomic_set(&new_smi->req_events, 0);
> new_smi->run_to_completion = false;
> for (i = 0; i < SI_NUM_STATS; i++)
> - atomic_set(&new_smi->stats[i], 0);
> + counter_atomic32_set(&new_smi->stats[i], 0);
>
> new_smi->interrupt_disabled = true;
> atomic_set(&new_smi->need_watch, 0);
> --
> 2.25.1
>