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SubjectRe: [PATCH -v2] lib/notifier-error-inject: fix error when writing errno to debugfs file
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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)

--
Thanks,

David / dhildenb

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