From 71c9f0b00307e6ee703eef9eba91e7640731c458 Mon Sep 17 00:00:00 2001 From: Brian Behlendorf Date: Tue, 23 Oct 2012 09:17:29 -0700 Subject: [PATCH] Make kstat.ks_update() callback atomic Move the kstat ks_update() callback under the ks_lock. This enables dynamically sized kstats without modification to the kstat API. * Create a kstat with the KSTAT_FLAG_VIRTUAL flag. * Register a ->ks_update() callback which does: o Frees any existing ks_data buffer. o Set ks_data_size to the kstat array size. o Set ks_data to an allocated buffer of size ks_data_size o Populate the array of buffers with the required data. The buffer allocated in the ks_update() callback is guaranteed to remain allocated and valid while the proc sequence handler iterates over the buffer. The lock will not be dropped until kstat_seq_stop() function is run making it safe for concurrent access. To allow the ks_update() callback to perform memory allocations the lock was changed to a mutex. Signed-off-by: Brian Behlendorf --- include/sys/kstat.h | 3 ++- module/spl/spl-kstat.c | 12 +++++++----- 2 files changed, 9 insertions(+), 6 deletions(-) diff --git a/include/sys/kstat.h b/include/sys/kstat.h index e4c88c82b..45386d49a 100644 --- a/include/sys/kstat.h +++ b/include/sys/kstat.h @@ -30,6 +30,7 @@ #include #include #include +#include #define KSTAT_STRLEN 31 @@ -98,7 +99,7 @@ typedef struct kstat_s { struct proc_dir_entry *ks_proc; /* proc linkage */ kstat_update_t *ks_update; /* dynamic updates */ void *ks_private; /* private data */ - spinlock_t ks_lock; /* kstat data lock */ + kmutex_t ks_lock; /* kstat data lock */ struct list_head ks_list; /* kstat linkage */ } kstat_t; diff --git a/module/spl/spl-kstat.c b/module/spl/spl-kstat.c index 48fab972b..164a8436d 100644 --- a/module/spl/spl-kstat.c +++ b/module/spl/spl-kstat.c @@ -267,10 +267,11 @@ kstat_seq_start(struct seq_file *f, loff_t *pos) ASSERT(ksp->ks_magic == KS_MAGIC); SENTRY; + mutex_enter(&ksp->ks_lock); + /* Dynamically update kstat, on error existing kstats are used */ (void) ksp->ks_update(ksp, KSTAT_READ); - spin_lock(&ksp->ks_lock); ksp->ks_snaptime = gethrtime(); if (!n) @@ -302,7 +303,7 @@ kstat_seq_stop(struct seq_file *f, void *v) kstat_t *ksp = (kstat_t *)f->private; ASSERT(ksp->ks_magic == KS_MAGIC); - spin_unlock(&ksp->ks_lock); + mutex_exit(&ksp->ks_lock); } static struct seq_operations kstat_seq_ops = { @@ -360,7 +361,7 @@ __kstat_create(const char *ks_module, int ks_instance, const char *ks_name, spin_unlock(&kstat_lock); ksp->ks_magic = KS_MAGIC; - spin_lock_init(&ksp->ks_lock); + mutex_init(&ksp->ks_lock, NULL, MUTEX_DEFAULT, NULL); INIT_LIST_HEAD(&ksp->ks_list); ksp->ks_crtime = gethrtime(); @@ -445,11 +446,11 @@ __kstat_install(kstat_t *ksp) if (de_name == NULL) SGOTO(out, rc = -EUNATCH); - spin_lock(&ksp->ks_lock); + mutex_enter(&ksp->ks_lock); ksp->ks_proc = de_name; de_name->proc_fops = &proc_kstat_operations; de_name->data = (void *)ksp; - spin_unlock(&ksp->ks_lock); + mutex_exit(&ksp->ks_lock); out: if (rc) { spin_lock(&kstat_lock); @@ -482,6 +483,7 @@ __kstat_delete(kstat_t *ksp) if (!(ksp->ks_flags & KSTAT_FLAG_VIRTUAL)) kmem_free(ksp->ks_data, ksp->ks_data_size); + mutex_destroy(&ksp->ks_lock); kmem_free(ksp, sizeof(*ksp)); return; -- 2.40.0