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author | Steven Rostedt <srostedt@redhat.com> | 2011-12-20 04:07:36 +0400 |
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committer | Steven Rostedt <rostedt@goodmis.org> | 2011-12-21 16:23:11 +0400 |
commit | 06a51d9307380c78bb5c92e68fc80ad2c7d7f890 (patch) | |
tree | e0f38e8780f92937e8f19f17b8bf9eff6bcc3137 /kernel/trace/ftrace.c | |
parent | c842e975520f8ab09e293cc92f51a1f396251fd5 (diff) | |
download | linux-06a51d9307380c78bb5c92e68fc80ad2c7d7f890.tar.xz |
ftrace: Create ftrace_hash_empty() helper routine
There are two types of hashes in the ftrace_ops; one type
is the filter_hash and the other is the notrace_hash. Either
one may be null, meaning it has no elements. But when elements
are added, the hash is allocated.
Throughout the code, a check needs to be made to see if a hash
exists or the hash has elements, but the check if the hash exists
is usually missing causing the possible "NULL pointer dereference bug".
Add a helper routine called "ftrace_hash_empty()" that returns
true if the hash doesn't exist or its count is zero. As they mean
the same thing.
Last-bug-reported-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace/ftrace.c')
-rw-r--r-- | kernel/trace/ftrace.c | 28 |
1 files changed, 17 insertions, 11 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index a383d6c67bfa..e1ee07f81ca2 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -999,6 +999,11 @@ static struct ftrace_page *ftrace_new_pgs; static struct ftrace_page *ftrace_pages_start; static struct ftrace_page *ftrace_pages; +static bool ftrace_hash_empty(struct ftrace_hash *hash) +{ + return !hash || !hash->count; +} + static struct ftrace_func_entry * ftrace_lookup_ip(struct ftrace_hash *hash, unsigned long ip) { @@ -1007,7 +1012,7 @@ ftrace_lookup_ip(struct ftrace_hash *hash, unsigned long ip) struct hlist_head *hhd; struct hlist_node *n; - if (!hash->count) + if (ftrace_hash_empty(hash)) return NULL; if (hash->size_bits > 0) @@ -1151,7 +1156,7 @@ alloc_and_copy_ftrace_hash(int size_bits, struct ftrace_hash *hash) return NULL; /* Empty hash? */ - if (!hash || !hash->count) + if (ftrace_hash_empty(hash)) return new_hash; size = 1 << hash->size_bits; @@ -1276,9 +1281,9 @@ ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip) filter_hash = rcu_dereference_raw(ops->filter_hash); notrace_hash = rcu_dereference_raw(ops->notrace_hash); - if ((!filter_hash || !filter_hash->count || + if ((ftrace_hash_empty(filter_hash) || ftrace_lookup_ip(filter_hash, ip)) && - (!notrace_hash || !notrace_hash->count || + (ftrace_hash_empty(notrace_hash) || !ftrace_lookup_ip(notrace_hash, ip))) ret = 1; else @@ -1371,7 +1376,7 @@ static void __ftrace_hash_rec_update(struct ftrace_ops *ops, if (filter_hash) { hash = ops->filter_hash; other_hash = ops->notrace_hash; - if (!hash || !hash->count) + if (ftrace_hash_empty(hash)) all = 1; } else { inc = !inc; @@ -1381,7 +1386,7 @@ static void __ftrace_hash_rec_update(struct ftrace_ops *ops, * If the notrace hash has no items, * then there's nothing to do. */ - if (!hash || !hash->count) + if (ftrace_hash_empty(hash)) return; } @@ -1398,8 +1403,8 @@ static void __ftrace_hash_rec_update(struct ftrace_ops *ops, if (!other_hash || !ftrace_lookup_ip(other_hash, rec->ip)) match = 1; } else { - in_hash = hash && !!ftrace_lookup_ip(hash, rec->ip); - in_other_hash = other_hash && !!ftrace_lookup_ip(other_hash, rec->ip); + in_hash = !!ftrace_lookup_ip(hash, rec->ip); + in_other_hash = !!ftrace_lookup_ip(other_hash, rec->ip); /* * @@ -1407,7 +1412,7 @@ static void __ftrace_hash_rec_update(struct ftrace_ops *ops, if (filter_hash && in_hash && !in_other_hash) match = 1; else if (!filter_hash && in_hash && - (in_other_hash || !other_hash->count)) + (in_other_hash || ftrace_hash_empty(other_hash))) match = 1; } if (!match) @@ -1950,7 +1955,7 @@ static int ops_traces_mod(struct ftrace_ops *ops) struct ftrace_hash *hash; hash = ops->filter_hash; - return !!(!hash || !hash->count); + return ftrace_hash_empty(hash); } static int ftrace_update_code(struct module *mod) @@ -2320,7 +2325,8 @@ static void *t_start(struct seq_file *m, loff_t *pos) * off, we can short cut and just print out that all * functions are enabled. */ - if (iter->flags & FTRACE_ITER_FILTER && !ops->filter_hash->count) { + if (iter->flags & FTRACE_ITER_FILTER && + ftrace_hash_empty(ops->filter_hash)) { if (*pos > 0) return t_hash_start(m, pos); iter->flags |= FTRACE_ITER_PRINTALL; |