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nfp: remove cpp mutex cache

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CPP mutex cache was introduced to work around the fact that the
same host could successfully acquire a lock multiple times.  It
used to collapse multiple users to the same struct nfp_cpp_mutex
and track use count.  Unfortunately it's racy.  Since we now force
all nfp_mutex_lock() callers within the host to actually succeed
at acquiring the lock we no longer need the cache, let's remove it.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jakub Kicinski 2017-03-21 17:59:09 -07:00 committed by David S. Miller
parent f1ba63ec90
commit 832ff9482e
1 changed files with 2 additions and 41 deletions
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43
drivers/net/ethernet/netronome/nfp/nfpcore/nfp_cppcore.c
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@ -66,10 +66,8 @@ struct nfp_cpp_resource {
};
struct nfp_cpp_mutex {
struct list_head list;
struct nfp_cpp *cpp;
int target;
u16 usage;
u16 depth;
unsigned long long address;
u32 key;
@ -86,7 +84,6 @@ struct nfp_cpp {
const struct nfp_cpp_operations *op;
struct list_head resource_list; /* NFP CPP resource list */
struct list_head mutex_cache; /* Mutex cache */
rwlock_t resource_lock;
wait_queue_head_t waitq;
@ -187,24 +184,6 @@ void nfp_cpp_free(struct nfp_cpp *cpp)
{
struct nfp_cpp_area_cache *cache, *ctmp;
struct nfp_cpp_resource *res, *rtmp;
struct nfp_cpp_mutex *mutex, *mtmp;
/* There should be no mutexes in the cache at this point. */
WARN_ON(!list_empty(&cpp->mutex_cache));
/* .. but if there are, unlock them and complain. */
list_for_each_entry_safe(mutex, mtmp, &cpp->mutex_cache, list) {
dev_err(cpp->dev.parent, "Dangling mutex: @%d::0x%llx, %d locks held by %d owners\n",
mutex->target, (unsigned long long)mutex->address,
mutex->depth, mutex->usage);
/* Forcing an unlock */
mutex->depth = 1;
nfp_cpp_mutex_unlock(mutex);
/* Forcing a free */
mutex->usage = 1;
nfp_cpp_mutex_free(mutex);
}
/* Remove all caches */
list_for_each_entry_safe(cache, ctmp, &cpp->area_cache_list, entry) {
@ -1127,7 +1106,6 @@ nfp_cpp_from_operations(const struct nfp_cpp_operations *ops,
rwlock_init(&cpp->resource_lock);
init_waitqueue_head(&cpp->waitq);
lockdep_set_class(&cpp->resource_lock, &nfp_cpp_resource_lock_key);
INIT_LIST_HEAD(&cpp->mutex_cache);
INIT_LIST_HEAD(&cpp->resource_list);
INIT_LIST_HEAD(&cpp->area_cache_list);
mutex_init(&cpp->area_cache_mutex);
@ -1536,14 +1514,6 @@ struct nfp_cpp_mutex *nfp_cpp_mutex_alloc(struct nfp_cpp *cpp, int target,
if (err)
return NULL;
/* Look for mutex on cache list */
list_for_each_entry(mutex, &cpp->mutex_cache, list) {
if (mutex->target == target && mutex->address == address) {
mutex->usage++;
return mutex;
}
}
err = nfp_cpp_readl(cpp, mur, address + 4, &tmp);
if (err < 0)
return NULL;
@ -1560,10 +1530,6 @@ struct nfp_cpp_mutex *nfp_cpp_mutex_alloc(struct nfp_cpp *cpp, int target,
mutex->address = address;
mutex->key = key;
mutex->depth = 0;
mutex->usage = 1;
/* Add mutex to cache list */
list_add(&mutex->list, &cpp->mutex_cache);
return mutex;
}
@ -1574,11 +1540,6 @@ struct nfp_cpp_mutex *nfp_cpp_mutex_alloc(struct nfp_cpp *cpp, int target,
*/
void nfp_cpp_mutex_free(struct nfp_cpp_mutex *mutex)
{
if (--mutex->usage)
return;
/* Remove mutex from cache */
list_del(&mutex->list);
kfree(mutex);
}
@ -1611,8 +1572,8 @@ int nfp_cpp_mutex_lock(struct nfp_cpp_mutex *mutex)
if (time_is_before_eq_jiffies(warn_at)) {
warn_at = jiffies + 60 * HZ;
dev_warn(mutex->cpp->dev.parent,
"Warning: waiting for NFP mutex [usage:%hd depth:%hd target:%d addr:%llx key:%08x]\n",
mutex->usage, mutex->depth,
"Warning: waiting for NFP mutex [depth:%hd target:%d addr:%llx key:%08x]\n",
mutex->depth,
mutex->target, mutex->address, mutex->key);
}
}