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Tue, 03 Mar 2026 23:47:29 -0800 (PST) From: Yafang Shao To: peterz@infradead.org, mingo@redhat.com, will@kernel.org, boqun@kernel.org, longman@redhat.com, rostedt@goodmis.org, mhiramat@kernel.org, mark.rutland@arm.com, mathieu.desnoyers@efficios.com Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org, Yafang Shao Subject: [RFC PATCH 2/2] ftrace: disable optimistic spinning for ftrace_lock Date: Wed, 4 Mar 2026 15:46:50 +0800 Message-ID: <20260304074650.58165-3-laoar.shao@gmail.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20260304074650.58165-1-laoar.shao@gmail.com> References: <20260304074650.58165-1-laoar.shao@gmail.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit mutex_lock_nospin() is used for ftrace_lock to selectively disable optimistic spinning. Signed-off-by: Yafang Shao --- kernel/trace/ftrace.c | 52 +++++++++++++++++++++---------------------- 1 file changed, 26 insertions(+), 26 deletions(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 827fb9a0bf0d..b8cca4f76118 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -1284,7 +1284,7 @@ static void clear_ftrace_mod_list(struct list_head *head) if (!head) return; - mutex_lock(&ftrace_lock); + mutex_lock_nospin(&ftrace_lock); list_for_each_entry_safe(p, n, head, list) free_ftrace_mod(p); mutex_unlock(&ftrace_lock); @@ -4254,7 +4254,7 @@ static void *t_start(struct seq_file *m, loff_t *pos) void *p = NULL; loff_t l; - mutex_lock(&ftrace_lock); + mutex_lock_nospin(&ftrace_lock); if (unlikely(ftrace_disabled)) return NULL; @@ -4362,7 +4362,7 @@ static __init void ftrace_check_work_func(struct work_struct *work) struct ftrace_page *pg; struct dyn_ftrace *rec; - mutex_lock(&ftrace_lock); + mutex_lock_nospin(&ftrace_lock); do_for_each_ftrace_rec(pg, rec) { test_for_valid_rec(rec); } while_for_each_ftrace_rec(); @@ -5123,7 +5123,7 @@ static void process_mod_list(struct list_head *head, struct ftrace_ops *ops, if (!new_hash) goto out; /* warn? */ - mutex_lock(&ftrace_lock); + mutex_lock_nospin(&ftrace_lock); list_for_each_entry_safe(ftrace_mod, n, head, list) { @@ -5159,7 +5159,7 @@ static void process_mod_list(struct list_head *head, struct ftrace_ops *ops, if (enable && list_empty(head)) new_hash->flags &= ~FTRACE_HASH_FL_MOD; - mutex_lock(&ftrace_lock); + mutex_lock_nospin(&ftrace_lock); ftrace_hash_move_and_update_ops(ops, orig_hash, new_hash, enable); @@ -5465,7 +5465,7 @@ register_ftrace_function_probe(char *glob, struct trace_array *tr, return -EINVAL; - mutex_lock(&ftrace_lock); + mutex_lock_nospin(&ftrace_lock); /* Check if the probe_ops is already registered */ list_for_each_entry(iter, &tr->func_probes, list) { if (iter->probe_ops == probe_ops) { @@ -5540,7 +5540,7 @@ register_ftrace_function_probe(char *glob, struct trace_array *tr, } } - mutex_lock(&ftrace_lock); + mutex_lock_nospin(&ftrace_lock); if (!count) { /* Nothing was added? */ @@ -5619,7 +5619,7 @@ unregister_ftrace_function_probe_func(char *glob, struct trace_array *tr, return -EINVAL; } - mutex_lock(&ftrace_lock); + mutex_lock_nospin(&ftrace_lock); /* Check if the probe_ops is already registered */ list_for_each_entry(iter, &tr->func_probes, list) { if (iter->probe_ops == probe_ops) { @@ -5679,7 +5679,7 @@ unregister_ftrace_function_probe_func(char *glob, struct trace_array *tr, goto out_unlock; } - mutex_lock(&ftrace_lock); + mutex_lock_nospin(&ftrace_lock); WARN_ON(probe->ref < count); @@ -5943,7 +5943,7 @@ ftrace_set_hash(struct ftrace_ops *ops, unsigned char *buf, int len, goto out_regex_unlock; } - mutex_lock(&ftrace_lock); + mutex_lock_nospin(&ftrace_lock); ret = ftrace_hash_move_and_update_ops(ops, orig_hash, hash, enable); mutex_unlock(&ftrace_lock); @@ -6205,7 +6205,7 @@ __modify_ftrace_direct(struct ftrace_ops *ops, unsigned long addr) * Now the ftrace_ops_list_func() is called to do the direct callers. * We can safely change the direct functions attached to each entry. */ - mutex_lock(&ftrace_lock); + mutex_lock_nospin(&ftrace_lock); size = 1 << hash->size_bits; for (i = 0; i < size; i++) { @@ -6625,7 +6625,7 @@ int update_ftrace_direct_mod(struct ftrace_ops *ops, struct ftrace_hash *hash, b * Now the ftrace_ops_list_func() is called to do the direct callers. * We can safely change the direct functions attached to each entry. */ - mutex_lock(&ftrace_lock); + mutex_lock_nospin(&ftrace_lock); size = 1 << hash->size_bits; for (i = 0; i < size; i++) { @@ -6980,7 +6980,7 @@ int ftrace_regex_release(struct inode *inode, struct file *file) } else orig_hash = &iter->ops->func_hash->notrace_hash; - mutex_lock(&ftrace_lock); + mutex_lock_nospin(&ftrace_lock); ftrace_hash_move_and_update_ops(iter->ops, orig_hash, iter->hash, filter_hash); mutex_unlock(&ftrace_lock); @@ -7464,7 +7464,7 @@ void ftrace_create_filter_files(struct ftrace_ops *ops, */ void ftrace_destroy_filter_files(struct ftrace_ops *ops) { - mutex_lock(&ftrace_lock); + mutex_lock_nospin(&ftrace_lock); if (ops->flags & FTRACE_OPS_FL_ENABLED) ftrace_shutdown(ops, 0); ops->flags |= FTRACE_OPS_FL_DELETED; @@ -7571,7 +7571,7 @@ static int ftrace_process_locs(struct module *mod, if (!start_pg) return -ENOMEM; - mutex_lock(&ftrace_lock); + mutex_lock_nospin(&ftrace_lock); /* * Core and each module needs their own pages, as @@ -7868,7 +7868,7 @@ void ftrace_release_mod(struct module *mod) struct ftrace_page *tmp_page = NULL; struct ftrace_page *pg; - mutex_lock(&ftrace_lock); + mutex_lock_nospin(&ftrace_lock); /* * To avoid the UAF problem after the module is unloaded, the @@ -7938,7 +7938,7 @@ void ftrace_module_enable(struct module *mod) struct dyn_ftrace *rec; struct ftrace_page *pg; - mutex_lock(&ftrace_lock); + mutex_lock_nospin(&ftrace_lock); if (ftrace_disabled) goto out_unlock; @@ -8267,7 +8267,7 @@ void ftrace_free_mem(struct module *mod, void *start_ptr, void *end_ptr) key.ip = start; key.flags = end; /* overload flags, as it is unsigned long */ - mutex_lock(&ftrace_lock); + mutex_lock_nospin(&ftrace_lock); /* * If we are freeing module init memory, then check if @@ -8686,7 +8686,7 @@ static void clear_ftrace_pids(struct trace_array *tr, int type) void ftrace_clear_pids(struct trace_array *tr) { - mutex_lock(&ftrace_lock); + mutex_lock_nospin(&ftrace_lock); clear_ftrace_pids(tr, TRACE_PIDS | TRACE_NO_PIDS); @@ -8695,7 +8695,7 @@ void ftrace_clear_pids(struct trace_array *tr) static void ftrace_pid_reset(struct trace_array *tr, int type) { - mutex_lock(&ftrace_lock); + mutex_lock_nospin(&ftrace_lock); clear_ftrace_pids(tr, type); ftrace_update_pid_func(); @@ -8713,7 +8713,7 @@ static void *fpid_start(struct seq_file *m, loff_t *pos) struct trace_pid_list *pid_list; struct trace_array *tr = m->private; - mutex_lock(&ftrace_lock); + mutex_lock_nospin(&ftrace_lock); rcu_read_lock_sched(); pid_list = rcu_dereference_sched(tr->function_pids); @@ -8766,7 +8766,7 @@ static void *fnpid_start(struct seq_file *m, loff_t *pos) struct trace_pid_list *pid_list; struct trace_array *tr = m->private; - mutex_lock(&ftrace_lock); + mutex_lock_nospin(&ftrace_lock); rcu_read_lock_sched(); pid_list = rcu_dereference_sched(tr->function_no_pids); @@ -9057,7 +9057,7 @@ static int prepare_direct_functions_for_ipmodify(struct ftrace_ops *ops) unsigned long ip = entry->ip; bool found_op = false; - mutex_lock(&ftrace_lock); + mutex_lock_nospin(&ftrace_lock); do_for_each_ftrace_op(op, ftrace_ops_list) { if (!(op->flags & FTRACE_OPS_FL_DIRECT)) continue; @@ -9106,7 +9106,7 @@ static void cleanup_direct_functions_after_ipmodify(struct ftrace_ops *ops) unsigned long ip = entry->ip; bool found_op = false; - mutex_lock(&ftrace_lock); + mutex_lock_nospin(&ftrace_lock); do_for_each_ftrace_op(op, ftrace_ops_list) { if (!(op->flags & FTRACE_OPS_FL_DIRECT)) continue; @@ -9153,7 +9153,7 @@ static int register_ftrace_function_nolock(struct ftrace_ops *ops) ftrace_ops_init(ops); - mutex_lock(&ftrace_lock); + mutex_lock_nospin(&ftrace_lock); ret = ftrace_startup(ops, 0); @@ -9200,7 +9200,7 @@ int unregister_ftrace_function(struct ftrace_ops *ops) { int ret; - mutex_lock(&ftrace_lock); + mutex_lock_nospin(&ftrace_lock); ret = ftrace_shutdown(ops, 0); mutex_unlock(&ftrace_lock); -- 2.47.3