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Commit 550d1f5b authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'trace-v5.2-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace 

Pull tracing fixes from Steven Rostedt:
 "This includes three fixes:

   - Fix a deadlock from a previous fix to keep module loading and
     function tracing text modifications from stepping on each other
     (this has a few patches to help document the issue in comments)

   - Fix a crash when the snapshot buffer gets out of sync with the main
     ring buffer

   - Fix a memory leak when reading the memory logs"

* tag 'trace-v5.2-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  ftrace/x86: Anotate text_mutex split between ftrace_arch_code_modify_post_process() and ftrace_arch_code_modify_prepare()
  tracing/snapshot: Resize spare buffer if size changed
  tracing: Fix memory leak in tracing_err_log_open()
  ftrace/x86: Add a comment to why we take text_mutex in ftrace_arch_code_modify_prepare()
  ftrace/x86: Remove possible deadlock between register_kprobe() and ftrace_run_update_code()
parents 179c96d9 074376ac

arch/x86/kernel/ftrace.c

+10 −0
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ 
#include <linux/init.h>

#include <linux/list.h>

#include <linux/module.h>

#include <linux/memory.h>



#include <trace/syscall.h>
@@ -34,16 +35,25 @@ 
#ifdef CONFIG_DYNAMIC_FTRACE



int ftrace_arch_code_modify_prepare(void)

    __acquires(&text_mutex)

{

	/*

	 * Need to grab text_mutex to prevent a race from module loading

	 * and live kernel patching from changing the text permissions while

	 * ftrace has it set to "read/write".

	 */

	mutex_lock(&text_mutex);

	set_kernel_text_rw();

	set_all_modules_text_rw();

	return 0;

}



int ftrace_arch_code_modify_post_process(void)

    __releases(&text_mutex)

{

	set_all_modules_text_ro();

	set_kernel_text_ro();

	mutex_unlock(&text_mutex);

	return 0;

}

kernel/trace/ftrace.c

+1 −9
Original line number Diff line number Diff line
@@ -34,7 +34,6 @@ 
#include <linux/hash.h>

#include <linux/rcupdate.h>

#include <linux/kprobes.h>

#include <linux/memory.h>



#include <trace/events/sched.h>
@@ -2611,12 +2610,10 @@ static void ftrace_run_update_code(int command) 
{

	int ret;



	mutex_lock(&text_mutex);



	ret = ftrace_arch_code_modify_prepare();

	FTRACE_WARN_ON(ret);

	if (ret)

		goto out_unlock;

		return;



	/*

	 * By default we use stop_machine() to modify the code.
@@ -2628,9 +2625,6 @@ static void ftrace_run_update_code(int command) 


	ret = ftrace_arch_code_modify_post_process();

	FTRACE_WARN_ON(ret);



out_unlock:

	mutex_unlock(&text_mutex);

}



static void ftrace_run_modify_code(struct ftrace_ops *ops, int command,
@@ -5784,7 +5778,6 @@ void ftrace_module_enable(struct module *mod) 
	struct ftrace_page *pg;



	mutex_lock(&ftrace_lock);

	mutex_lock(&text_mutex);



	if (ftrace_disabled)

		goto out_unlock;
@@ -5846,7 +5839,6 @@ void ftrace_module_enable(struct module *mod) 
		ftrace_arch_code_modify_post_process();



 out_unlock:

	mutex_unlock(&text_mutex);

	mutex_unlock(&ftrace_lock);



	process_cached_mods(mod->name);

kernel/trace/trace.c

+19 −5
Original line number Diff line number Diff line
@@ -6719,11 +6719,13 @@ tracing_snapshot_write(struct file *filp, const char __user *ubuf, size_t cnt, 
			break;

		}

#endif

		if (!tr->allocated_snapshot) {

		if (tr->allocated_snapshot)

			ret = resize_buffer_duplicate_size(&tr->max_buffer,

					&tr->trace_buffer, iter->cpu_file);

		else

			ret = tracing_alloc_snapshot_instance(tr);

		if (ret < 0)

			break;

		}

		local_irq_disable();

		/* Now, we're going to swap */

		if (iter->cpu_file == RING_BUFFER_ALL_CPUS)
@@ -7126,12 +7128,24 @@ static ssize_t tracing_err_log_write(struct file *file, 
	return count;

}



static int tracing_err_log_release(struct inode *inode, struct file *file)

{

	struct trace_array *tr = inode->i_private;



	trace_array_put(tr);



	if (file->f_mode & FMODE_READ)

		seq_release(inode, file);



	return 0;

}



static const struct file_operations tracing_err_log_fops = {

	.open           = tracing_err_log_open,

	.write		= tracing_err_log_write,

	.read           = seq_read,

	.llseek         = seq_lseek,

	.release	= tracing_release_generic_tr,

	.release        = tracing_err_log_release,

};



static int tracing_buffers_open(struct inode *inode, struct file *filp)