Revision bc94632ceb4b4af47b2c86f8f11177884821fb94 authored by Linus Torvalds on 19 June 2022, 14:37:29 UTC, committed by Linus Torvalds on 19 June 2022, 14:37:29 UTC
Pull char/misc driver fixes for real from Greg KH: "Let's tag the proper branch this time... Here are some small char/misc driver fixes for 5.19-rc3 that resolve some reported issues. They include: - mei driver fixes - comedi driver fix - rtsx build warning fix - fsl-mc-bus driver fix All of these have been in linux-next for a while with no reported issues" This is what the merge in commit f0ec9c65a8d6 _should_ have merged, but Greg fat-fingered the pull request and I got some small changes from linux-next instead there. Credit to Nathan Chancellor for eagle-eyes. Link: https://lore.kernel.org/all/Yqywy+Md2AfGDu8v@dev-arch.thelio-3990X/ * tag 'char-misc-5.19-rc3-take2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: bus: fsl-mc-bus: fix KASAN use-after-free in fsl_mc_bus_remove() mei: me: add raptor lake point S DID mei: hbm: drop capability response on early shutdown mei: me: set internal pg flag to off on hardware reset misc: rtsx: Fix clang -Wsometimes-uninitialized in rts5261_init_from_hw() comedi: vmk80xx: fix expression for tx buffer size
lockref.c
// SPDX-License-Identifier: GPL-2.0
#include <linux/export.h>
#include <linux/lockref.h>
#if USE_CMPXCHG_LOCKREF
/*
* Note that the "cmpxchg()" reloads the "old" value for the
* failure case.
*/
#define CMPXCHG_LOOP(CODE, SUCCESS) do { \
int retry = 100; \
struct lockref old; \
BUILD_BUG_ON(sizeof(old) != 8); \
old.lock_count = READ_ONCE(lockref->lock_count); \
while (likely(arch_spin_value_unlocked(old.lock.rlock.raw_lock))) { \
struct lockref new = old; \
CODE \
if (likely(try_cmpxchg64_relaxed(&lockref->lock_count, \
&old.lock_count, \
new.lock_count))) { \
SUCCESS; \
} \
if (!--retry) \
break; \
cpu_relax(); \
} \
} while (0)
#else
#define CMPXCHG_LOOP(CODE, SUCCESS) do { } while (0)
#endif
/**
* lockref_get - Increments reference count unconditionally
* @lockref: pointer to lockref structure
*
* This operation is only valid if you already hold a reference
* to the object, so you know the count cannot be zero.
*/
void lockref_get(struct lockref *lockref)
{
CMPXCHG_LOOP(
new.count++;
,
return;
);
spin_lock(&lockref->lock);
lockref->count++;
spin_unlock(&lockref->lock);
}
EXPORT_SYMBOL(lockref_get);
/**
* lockref_get_not_zero - Increments count unless the count is 0 or dead
* @lockref: pointer to lockref structure
* Return: 1 if count updated successfully or 0 if count was zero
*/
int lockref_get_not_zero(struct lockref *lockref)
{
int retval;
CMPXCHG_LOOP(
new.count++;
if (old.count <= 0)
return 0;
,
return 1;
);
spin_lock(&lockref->lock);
retval = 0;
if (lockref->count > 0) {
lockref->count++;
retval = 1;
}
spin_unlock(&lockref->lock);
return retval;
}
EXPORT_SYMBOL(lockref_get_not_zero);
/**
* lockref_put_not_zero - Decrements count unless count <= 1 before decrement
* @lockref: pointer to lockref structure
* Return: 1 if count updated successfully or 0 if count would become zero
*/
int lockref_put_not_zero(struct lockref *lockref)
{
int retval;
CMPXCHG_LOOP(
new.count--;
if (old.count <= 1)
return 0;
,
return 1;
);
spin_lock(&lockref->lock);
retval = 0;
if (lockref->count > 1) {
lockref->count--;
retval = 1;
}
spin_unlock(&lockref->lock);
return retval;
}
EXPORT_SYMBOL(lockref_put_not_zero);
/**
* lockref_get_or_lock - Increments count unless the count is 0 or dead
* @lockref: pointer to lockref structure
* Return: 1 if count updated successfully or 0 if count was zero
* and we got the lock instead.
*/
int lockref_get_or_lock(struct lockref *lockref)
{
CMPXCHG_LOOP(
new.count++;
if (old.count <= 0)
break;
,
return 1;
);
spin_lock(&lockref->lock);
if (lockref->count <= 0)
return 0;
lockref->count++;
spin_unlock(&lockref->lock);
return 1;
}
EXPORT_SYMBOL(lockref_get_or_lock);
/**
* lockref_put_return - Decrement reference count if possible
* @lockref: pointer to lockref structure
*
* Decrement the reference count and return the new value.
* If the lockref was dead or locked, return an error.
*/
int lockref_put_return(struct lockref *lockref)
{
CMPXCHG_LOOP(
new.count--;
if (old.count <= 0)
return -1;
,
return new.count;
);
return -1;
}
EXPORT_SYMBOL(lockref_put_return);
/**
* lockref_put_or_lock - decrements count unless count <= 1 before decrement
* @lockref: pointer to lockref structure
* Return: 1 if count updated successfully or 0 if count <= 1 and lock taken
*/
int lockref_put_or_lock(struct lockref *lockref)
{
CMPXCHG_LOOP(
new.count--;
if (old.count <= 1)
break;
,
return 1;
);
spin_lock(&lockref->lock);
if (lockref->count <= 1)
return 0;
lockref->count--;
spin_unlock(&lockref->lock);
return 1;
}
EXPORT_SYMBOL(lockref_put_or_lock);
/**
* lockref_mark_dead - mark lockref dead
* @lockref: pointer to lockref structure
*/
void lockref_mark_dead(struct lockref *lockref)
{
assert_spin_locked(&lockref->lock);
lockref->count = -128;
}
EXPORT_SYMBOL(lockref_mark_dead);
/**
* lockref_get_not_dead - Increments count unless the ref is dead
* @lockref: pointer to lockref structure
* Return: 1 if count updated successfully or 0 if lockref was dead
*/
int lockref_get_not_dead(struct lockref *lockref)
{
int retval;
CMPXCHG_LOOP(
new.count++;
if (old.count < 0)
return 0;
,
return 1;
);
spin_lock(&lockref->lock);
retval = 0;
if (lockref->count >= 0) {
lockref->count++;
retval = 1;
}
spin_unlock(&lockref->lock);
return retval;
}
EXPORT_SYMBOL(lockref_get_not_dead);
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