On 17.09.22 09:14, Akinobu Mita wrote:

The simple attribute files do not accept a negative value since the commit 488dac0c9237 ("libfs: fix error cast of negative value in simple_attr_write()"), so we can no longer use DEFINE_SIMPLE_ATTRIBUTE() to define a file operations for errno value.

Fixes: 488dac0c9237 ("libfs: fix error cast of negative value in simple_attr_write()") Reported-by: Zhao Gongyi zhaogongyi@huawei.com Signed-off-by: Akinobu Mita akinobu.mita@gmail.com

But shouldn't we fix simple_attr_write() instead?

I mean, simple_attr_read() might use attr->fmt to print a signed value, but simple_attr_write() fails on signed values now?

I might be wrong, but there is a disconnect. I feel like simple_attr_write() should similarly make decisions based on attr->fmt.

---

v2: Fix Reported-by line

lib/notifier-error-inject.c | 38 ++++++++++++++++++++++++++++++------- 1 file changed, 31 insertions(+), 7 deletions(-)

diff --git a/lib/notifier-error-inject.c b/lib/notifier-error-inject.c index 21016b32d313..30ec41f58d53 100644 --- a/lib/notifier-error-inject.c +++ b/lib/notifier-error-inject.c @@ -3,20 +3,44 @@ #include "notifier-error-inject.h" -static int debugfs_errno_set(void *data, u64 val) +static int notifier_err_errno_show(struct seq_file *m, void *data) {

• *(int *)data = clamp_t(int, val, -MAX_ERRNO, 0);

• int *value = m->private;
• seq_printf(m, "%d\n", *value);
• return 0; }

-static int debugfs_errno_get(void *data, u64 *val) +static int notifier_err_errno_open(struct inode *inode, struct file *file) {

• *val = *(int *)data;
• return 0;

• return single_open(file, notifier_err_errno_show, inode->i_private);

+}

+static ssize_t notifier_err_errno_write(struct file *file, const char __user *ubuf, size_t len,

• 			loff_t *offp)
  

+{

• struct seq_file *m = file->private_data;
• int *value = m->private;
• int ret;
• ret = kstrtoint_from_user(ubuf, len, 0, value);
• if (ret)

• return ret;
  

• *value = clamp(*value, -MAX_ERRNO, 0);
• return len; }

-DEFINE_SIMPLE_ATTRIBUTE(fops_errno, debugfs_errno_get, debugfs_errno_set,

• 	"%lld\n");
  

+static const struct file_operations fops_errno = {

• .owner = THIS_MODULE,
• .open = notifier_err_errno_open,
• .read = seq_read,
• .write = notifier_err_errno_write,
• .llseek = seq_lseek,
• .release = single_release,

+}; static struct dentry *debugfs_create_errno(const char *name, umode_t mode, struct dentry *parent, int *value)