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Date: Wed, 21 Sep 2022 09:21:52 -0400
From: Waiman Long <longman@...hat.com>
To: Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>,
Boqun Feng <boqun.feng@...il.com>,
Steven Rostedt <rostedt@...dmis.org>
Cc: linux-kernel@...r.kernel.org, Waiman Long <longman@...hat.com>
Subject: [PATCH 2/2] tracing: Use proper do_arch_spin_lock() API
It was found that some tracing functions acquire a arch_spinlock_t with
preemption and irqs enabled. That can be problematic in case preemption
happens after acquiring the lock. Use the proper do_arch_spin_lock()
API with preemption disabled to make sure that this won't happen unless
it is obvious that either preemption or irqs has been disabled .
Signed-off-by: Waiman Long <longman@...hat.com>
---
kernel/trace/trace.c | 52 ++++++++++++++++++++------------------------
1 file changed, 24 insertions(+), 28 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index d3005279165d..cbb8520842ad 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1193,12 +1193,12 @@ void *tracing_cond_snapshot_data(struct trace_array *tr)
{
void *cond_data = NULL;
- arch_spin_lock(&tr->max_lock);
+ do_arch_spin_lock(&tr->max_lock);
if (tr->cond_snapshot)
cond_data = tr->cond_snapshot->cond_data;
- arch_spin_unlock(&tr->max_lock);
+ do_arch_spin_unlock(&tr->max_lock);
return cond_data;
}
@@ -1334,9 +1334,9 @@ int tracing_snapshot_cond_enable(struct trace_array *tr, void *cond_data,
goto fail_unlock;
}
- arch_spin_lock(&tr->max_lock);
+ do_arch_spin_lock(&tr->max_lock);
tr->cond_snapshot = cond_snapshot;
- arch_spin_unlock(&tr->max_lock);
+ do_arch_spin_unlock(&tr->max_lock);
mutex_unlock(&trace_types_lock);
@@ -1363,7 +1363,7 @@ int tracing_snapshot_cond_disable(struct trace_array *tr)
{
int ret = 0;
- arch_spin_lock(&tr->max_lock);
+ do_arch_spin_lock(&tr->max_lock);
if (!tr->cond_snapshot)
ret = -EINVAL;
@@ -1372,7 +1372,7 @@ int tracing_snapshot_cond_disable(struct trace_array *tr)
tr->cond_snapshot = NULL;
}
- arch_spin_unlock(&tr->max_lock);
+ do_arch_spin_unlock(&tr->max_lock);
return ret;
}
@@ -1819,7 +1819,7 @@ update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu,
return;
}
- arch_spin_lock(&tr->max_lock);
+ do_arch_spin_lock(&tr->max_lock);
/* Inherit the recordable setting from array_buffer */
if (ring_buffer_record_is_set_on(tr->array_buffer.buffer))
@@ -1836,7 +1836,7 @@ update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu,
__update_max_tr(tr, tsk, cpu);
out_unlock:
- arch_spin_unlock(&tr->max_lock);
+ do_arch_spin_unlock(&tr->max_lock);
}
/**
@@ -1862,7 +1862,7 @@ update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
return;
}
- arch_spin_lock(&tr->max_lock);
+ do_arch_spin_lock(&tr->max_lock);
ret = ring_buffer_swap_cpu(tr->max_buffer.buffer, tr->array_buffer.buffer, cpu);
@@ -1880,7 +1880,7 @@ update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
WARN_ON_ONCE(ret && ret != -EAGAIN && ret != -EBUSY);
__update_max_tr(tr, tsk, cpu);
- arch_spin_unlock(&tr->max_lock);
+ do_arch_spin_unlock(&tr->max_lock);
}
#endif /* CONFIG_TRACER_MAX_TRACE */
@@ -2413,7 +2413,7 @@ static int trace_save_cmdline(struct task_struct *tsk)
* nor do we want to disable interrupts,
* so if we miss here, then better luck next time.
*/
- if (!arch_spin_trylock(&trace_cmdline_lock))
+ if (!do_arch_spin_trylock(&trace_cmdline_lock))
return 0;
idx = savedcmd->map_pid_to_cmdline[tpid];
@@ -2427,7 +2427,7 @@ static int trace_save_cmdline(struct task_struct *tsk)
savedcmd->map_cmdline_to_pid[idx] = tsk->pid;
set_cmdline(idx, tsk->comm);
- arch_spin_unlock(&trace_cmdline_lock);
+ do_arch_spin_unlock(&trace_cmdline_lock);
return 1;
}
@@ -2461,13 +2461,11 @@ static void __trace_find_cmdline(int pid, char comm[])
void trace_find_cmdline(int pid, char comm[])
{
- preempt_disable();
- arch_spin_lock(&trace_cmdline_lock);
+ do_arch_spin_lock(&trace_cmdline_lock);
__trace_find_cmdline(pid, comm);
- arch_spin_unlock(&trace_cmdline_lock);
- preempt_enable();
+ do_arch_spin_unlock(&trace_cmdline_lock);
}
static int *trace_find_tgid_ptr(int pid)
@@ -5829,8 +5827,7 @@ static void *saved_cmdlines_start(struct seq_file *m, loff_t *pos)
void *v;
loff_t l = 0;
- preempt_disable();
- arch_spin_lock(&trace_cmdline_lock);
+ do_arch_spin_lock(&trace_cmdline_lock);
v = &savedcmd->map_cmdline_to_pid[0];
while (l <= *pos) {
@@ -5844,8 +5841,7 @@ static void *saved_cmdlines_start(struct seq_file *m, loff_t *pos)
static void saved_cmdlines_stop(struct seq_file *m, void *v)
{
- arch_spin_unlock(&trace_cmdline_lock);
- preempt_enable();
+ do_arch_spin_unlock(&trace_cmdline_lock);
}
static int saved_cmdlines_show(struct seq_file *m, void *v)
@@ -5890,9 +5886,9 @@ tracing_saved_cmdlines_size_read(struct file *filp, char __user *ubuf,
char buf[64];
int r;
- arch_spin_lock(&trace_cmdline_lock);
+ do_arch_spin_lock(&trace_cmdline_lock);
r = scnprintf(buf, sizeof(buf), "%u\n", savedcmd->cmdline_num);
- arch_spin_unlock(&trace_cmdline_lock);
+ do_arch_spin_unlock(&trace_cmdline_lock);
return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
}
@@ -5917,10 +5913,10 @@ static int tracing_resize_saved_cmdlines(unsigned int val)
return -ENOMEM;
}
- arch_spin_lock(&trace_cmdline_lock);
+ do_arch_spin_lock(&trace_cmdline_lock);
savedcmd_temp = savedcmd;
savedcmd = s;
- arch_spin_unlock(&trace_cmdline_lock);
+ do_arch_spin_unlock(&trace_cmdline_lock);
free_saved_cmdlines_buffer(savedcmd_temp);
return 0;
@@ -6373,10 +6369,10 @@ int tracing_set_tracer(struct trace_array *tr, const char *buf)
#ifdef CONFIG_TRACER_SNAPSHOT
if (t->use_max_tr) {
- arch_spin_lock(&tr->max_lock);
+ do_arch_spin_lock(&tr->max_lock);
if (tr->cond_snapshot)
ret = -EBUSY;
- arch_spin_unlock(&tr->max_lock);
+ do_arch_spin_unlock(&tr->max_lock);
if (ret)
goto out;
}
@@ -7436,10 +7432,10 @@ tracing_snapshot_write(struct file *filp, const char __user *ubuf, size_t cnt,
goto out;
}
- arch_spin_lock(&tr->max_lock);
+ do_arch_spin_lock(&tr->max_lock);
if (tr->cond_snapshot)
ret = -EBUSY;
- arch_spin_unlock(&tr->max_lock);
+ do_arch_spin_unlock(&tr->max_lock);
if (ret)
goto out;
--
2.31.1
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