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SUNRPC: Drop all entries from cache_detail when cache_purge() 

User always free the cache_detail after sunrpc_destroy_cache_detail(),
so, it must cleanup up entries that left in the cache_detail,
otherwise, NULL reference may be caused when using the left entries.

Also, NeriBrown suggests "write a stand-alone cache_purge()."

v3, move the cache_fresh_unlocked() out of write lock,
v2, a stand-alone cache_purge(), not only for sunrpc_destroy_cache_detail

Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
Reviewed-by: NeilBrown <neilb@suse.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
Kinglong Mee 2017-02-08 09:54:33 +08:00 committed by J. Bruce Fields
parent 81fa3275f9
commit 471a930ad7
1 changed files with 26 additions and 15 deletions
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41
net/sunrpc/cache.c
View File

@ -362,11 +362,6 @@ void sunrpc_destroy_cache_detail(struct cache_detail *cd)
cache_purge(cd);
spin_lock(&cache_list_lock);
write_lock(&cd->hash_lock);
if (cd->entries) {
write_unlock(&cd->hash_lock);
spin_unlock(&cache_list_lock);
goto out;
}
if (current_detail == cd)
current_detail = NULL;
list_del_init(&cd->others);
@ -376,9 +371,6 @@ void sunrpc_destroy_cache_detail(struct cache_detail *cd)
/* module must be being unloaded so its safe to kill the worker */
cancel_delayed_work_sync(&cache_cleaner);
}
return;
out:
printk(KERN_ERR "RPC: failed to unregister %s cache\n", cd->name);
}
EXPORT_SYMBOL_GPL(sunrpc_destroy_cache_detail);
@ -497,13 +489,32 @@ EXPORT_SYMBOL_GPL(cache_flush);
void cache_purge(struct cache_detail *detail)
{
time_t now = seconds_since_boot();
if (detail->flush_time >= now)
now = detail->flush_time + 1;
/* 'now' is the maximum value any 'last_refresh' can have */
detail->flush_time = now;
detail->nextcheck = seconds_since_boot();
cache_flush();
struct cache_head *ch = NULL;
struct hlist_head *head = NULL;
struct hlist_node *tmp = NULL;
int i = 0;
write_lock(&detail->hash_lock);
if (!detail->entries) {
write_unlock(&detail->hash_lock);
return;
}
dprintk("RPC: %d entries in %s cache\n", detail->entries, detail->name);
for (i = 0; i < detail->hash_size; i++) {
head = &detail->hash_table[i];
hlist_for_each_entry_safe(ch, tmp, head, cache_list) {
hlist_del_init(&ch->cache_list);
detail->entries--;
set_bit(CACHE_CLEANED, &ch->flags);
write_unlock(&detail->hash_lock);
cache_fresh_unlocked(ch, detail);
cache_put(ch, detail);
write_lock(&detail->hash_lock);
}
}
write_unlock(&detail->hash_lock);
}
EXPORT_SYMBOL_GPL(cache_purge);