Commit 9049f2f6 authored by Akinobu Mita's avatar Akinobu Mita Committed by Linus Torvalds
Browse files

fault-inject: parse as natural 1-based value for fail-nth write interface 

The value written to fail-nth file is parsed as 0-based.  Parsing as
one-based is more natural to understand and it enables to cancel the
previous setup by simply writing '0'.

This change also converts task->fail_nth from signed to unsigned int.

Link: http://lkml.kernel.org/r/1491490561-10485-3-git-send-email-akinobu.mita@gmail.com


Signed-off-by: default avatarAkinobu Mita <akinobu.mita@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ecaad81c

Documentation/fault-injection/fault-injection.txt

+3 −4
Original line number Diff line number Diff line
@@ -138,8 +138,8 @@ o proc entries 


- /proc/self/task/<current-tid>/fail-nth:



	Write to this file of integer N makes N-th call in the current task fail

	(N is 0-based). Read from this file returns a single char 'Y' or 'N'

	Write to this file of integer N makes N-th call in the task fail.

	Read from this file returns a single char 'Y' or 'N'

	that says if the fault setup with a previous write to this file was

	injected or not, and disables the fault if it wasn't yet injected.

	Note that this file enables all types of faults (slab, futex, etc).
@@ -320,7 +320,7 @@ int main() 
	system("echo N > /sys/kernel/debug/failslab/ignore-gfp-wait");

	sprintf(buf, "/proc/self/task/%ld/fail-nth", syscall(SYS_gettid));

	fail_nth = open(buf, O_RDWR);

	for (i = 0;; i++) {

	for (i = 1;; i++) {

		sprintf(buf, "%d", i);

		write(fail_nth, buf, strlen(buf));

		res = socketpair(AF_LOCAL, SOCK_STREAM, 0, fds);
@@ -339,7 +339,6 @@ int main() 


An example output:



0-th fault Y: res=-1/23

1-th fault Y: res=-1/23

2-th fault Y: res=-1/23

3-th fault Y: res=-1/12

fs/proc/base.c

+4 −5
Original line number Diff line number Diff line
@@ -1360,7 +1360,8 @@ static ssize_t proc_fail_nth_write(struct file *file, const char __user *buf, 
				   size_t count, loff_t *ppos)

{

	struct task_struct *task;

	int err, n;

	int err;

	unsigned int n;



	task = get_proc_task(file_inode(file));

	if (!task)
@@ -1368,12 +1369,10 @@ static ssize_t proc_fail_nth_write(struct file *file, const char __user *buf, 
	put_task_struct(task);

	if (task != current)

		return -EPERM;

	err = kstrtoint_from_user(buf, count, 0, &n);

	err = kstrtouint_from_user(buf, count, 0, &n);

	if (err)

		return err;

	if (n < 0 || n == INT_MAX)

		return -EINVAL;

	current->fail_nth = n + 1;

	current->fail_nth = n;

	return count;

}

include/linux/sched.h

+1 −1
Original line number Diff line number Diff line
@@ -974,7 +974,7 @@ struct task_struct { 


#ifdef CONFIG_FAULT_INJECTION

	int				make_it_fail;

	int fail_nth;

	unsigned int			fail_nth;

#endif

	/*

	 * When (nr_dirtied >= nr_dirtied_pause), it's time to call

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