[PATCH 06/11] cgroup: rstat lock indirection

JP Kobryn
2025-02-18T03:15:10Z

Instead of accessing the target lock directly via global var, access it
indirectly in the form of a new parameter. Also change the ordering of
the parameters to be consistent with the related per-cpu locking
function _cgroup_rstat_cpu_lock().

Signed-off-by: JP Kobryn <inwardvessel@gmail.com>
---
kernel/cgroup/rstat.c | 30 ++++++++++++++++--------------
1 file changed, 16 insertions(+), 14 deletions(-)

diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c
index 14dd8217db64..26c75629bca2 100644
--- a/kernel/cgroup/rstat.c
+++ b/kernel/cgroup/rstat.c
@@ -385,7 +385,7 @@ void bpf_rstat_flush(struct cgroup *cgrp, struct cgroup *parent, int cpu)
__bpf_hook_end();

/*
- * Helper functions for locking cgroup_rstat_lock.
+ * Helper functions for locking.
*
* This makes it easier to diagnose locking issues and contention in
* production environments. The parameter @cpu_in_loop indicate lock
@@ -393,24 +393,26 @@ __bpf_hook_end();
* value -1 is used when obtaining the main lock else this is the CPU
* number processed last.
*/
-static inline void __cgroup_rstat_lock(struct cgroup *cgrp, int cpu_in_loop)
- __acquires(&cgroup_rstat_lock)
+static inline void __cgroup_rstat_lock(spinlock_t *lock,
+ struct cgroup *cgrp, int cpu_in_loop)
+ __acquires(lock)
{
bool contended;

- contended = !spin_trylock_irq(&cgroup_rstat_lock);
+ contended = !spin_trylock_irq(lock);
if (contended) {
trace_cgroup_rstat_lock_contended(cgrp, cpu_in_loop, contended);
- spin_lock_irq(&cgroup_rstat_lock);
+ spin_lock_irq(lock);
}
trace_cgroup_rstat_locked(cgrp, cpu_in_loop, contended);
}

-static inline void __cgroup_rstat_unlock(struct cgroup *cgrp, int cpu_in_loop)
- __releases(&cgroup_rstat_lock)
+static inline void __cgroup_rstat_unlock(spinlock_t *lock,
+ struct cgroup *cgrp, int cpu_in_loop)
+ __releases(lock)
{
trace_cgroup_rstat_unlock(cgrp, cpu_in_loop, false);
- spin_unlock_irq(&cgroup_rstat_lock);
+ spin_unlock_irq(lock);
}

/* see cgroup_rstat_flush() */
@@ -434,10 +436,10 @@ static void cgroup_rstat_flush_locked(struct cgroup_rstat *rstat,
struct cgroup *cgrp;

cgrp = ops->cgroup_fn(rstat);
- __cgroup_rstat_unlock(cgrp, cpu);
+ __cgroup_rstat_unlock(&cgroup_rstat_lock, cgrp, cpu);
if (!cond_resched())
cpu_relax();
- __cgroup_rstat_lock(cgrp, cpu);
+ __cgroup_rstat_lock(&cgroup_rstat_lock, cgrp, cpu);
}
}
}
@@ -449,9 +451,9 @@ static void __cgroup_rstat_flush(struct cgroup_rstat *rstat,

might_sleep();
cgrp = ops->cgroup_fn(rstat);
- __cgroup_rstat_lock(cgrp, -1);
+ __cgroup_rstat_lock(&cgroup_rstat_lock, cgrp, -1);
cgroup_rstat_flush_locked(rstat, ops);
- __cgroup_rstat_unlock(cgrp, -1);
+ __cgroup_rstat_unlock(&cgroup_rstat_lock, cgrp, -1);
}

/**
@@ -487,7 +489,7 @@ static void __cgroup_rstat_flush_hold(struct cgroup_rstat *rstat,

might_sleep();
cgrp = ops->cgroup_fn(rstat);
- __cgroup_rstat_lock(cgrp, -1);
+ __cgroup_rstat_lock(&cgroup_rstat_lock, cgrp, -1);
cgroup_rstat_flush_locked(rstat, ops);
}

@@ -516,7 +518,7 @@ static void __cgroup_rstat_flush_release(struct cgroup_rstat *rstat,
struct cgroup *cgrp;

cgrp = ops->cgroup_fn(rstat);
- __cgroup_rstat_unlock(cgrp, -1);
+ __cgroup_rstat_unlock(&cgroup_rstat_lock, cgrp, -1);
}

/**
--
2.48.1