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

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