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rhashtable: Allow rhashtable to be used from irq-safe contexts

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rhashtable currently only does bh-safe synchronization making it impossible
to use from irq-safe contexts. Switch it to use irq-safe synchronization to
remove the restriction.

v2: Update the lock functions to return the ulong flags value and unlock
    functions to take the value directly instead of passing around the
    pointer. Suggested by Linus.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: David Vernet <dvernet@meta.com>
Acked-by: Josh Don <joshdon@google.com>
Acked-by: Hao Luo <haoluo@google.com>
Acked-by: Barret Rhoden <brho@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Tejun Heo
2022-12-06 11:36:32 -10:00
committed by David S. Miller
parent b602d00384
commit e47877c7aa
2 changed files with 46 additions and 31 deletions
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16
lib/rhashtable.c
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@@ -231,6 +231,7 @@ static int rhashtable_rehash_one(struct rhashtable *ht,
struct rhash_head *head, *next, *entry;
struct rhash_head __rcu **pprev = NULL;
unsigned int new_hash;
unsigned long flags;
if (new_tbl->nest)
goto out;
@@ -253,13 +254,14 @@ static int rhashtable_rehash_one(struct rhashtable *ht,
new_hash = head_hashfn(ht, new_tbl, entry);
rht_lock_nested(new_tbl, &new_tbl->buckets[new_hash], SINGLE_DEPTH_NESTING);
flags = rht_lock_nested(new_tbl, &new_tbl->buckets[new_hash],
SINGLE_DEPTH_NESTING);
head = rht_ptr(new_tbl->buckets + new_hash, new_tbl, new_hash);
RCU_INIT_POINTER(entry->next, head);
rht_assign_unlock(new_tbl, &new_tbl->buckets[new_hash], entry);
rht_assign_unlock(new_tbl, &new_tbl->buckets[new_hash], entry, flags);
if (pprev)
rcu_assign_pointer(*pprev, next);
@@ -276,18 +278,19 @@ static int rhashtable_rehash_chain(struct rhashtable *ht,
{
struct bucket_table *old_tbl = rht_dereference(ht->tbl, ht);
struct rhash_lock_head __rcu **bkt = rht_bucket_var(old_tbl, old_hash);
unsigned long flags;
int err;
if (!bkt)
return 0;
rht_lock(old_tbl, bkt);
flags = rht_lock(old_tbl, bkt);
while (!(err = rhashtable_rehash_one(ht, bkt, old_hash)))
;
if (err == -ENOENT)
err = 0;
rht_unlock(old_tbl, bkt);
rht_unlock(old_tbl, bkt, flags);
return err;
}
@@ -590,6 +593,7 @@ static void *rhashtable_try_insert(struct rhashtable *ht, const void *key,
struct bucket_table *new_tbl;
struct bucket_table *tbl;
struct rhash_lock_head __rcu **bkt;
unsigned long flags;
unsigned int hash;
void *data;
@@ -607,7 +611,7 @@ static void *rhashtable_try_insert(struct rhashtable *ht, const void *key,
new_tbl = rht_dereference_rcu(tbl->future_tbl, ht);
data = ERR_PTR(-EAGAIN);
} else {
rht_lock(tbl, bkt);
flags = rht_lock(tbl, bkt);
data = rhashtable_lookup_one(ht, bkt, tbl,
hash, key, obj);
new_tbl = rhashtable_insert_one(ht, bkt, tbl,
@@ -615,7 +619,7 @@ static void *rhashtable_try_insert(struct rhashtable *ht, const void *key,
if (PTR_ERR(new_tbl) != -EEXIST)
data = ERR_CAST(new_tbl);
rht_unlock(tbl, bkt);
rht_unlock(tbl, bkt, flags);
}
} while (!IS_ERR_OR_NULL(new_tbl));