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binfmt_misc: give the parse_command() results names

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parse_command() maps "0" to 1, "1" to 2 and "-1" to 3 and the write
handlers switch on those bare numbers, leaving every reader to redo
the mapping in their head. Name the commands and drop the per-case
comments that only existed to translate the numbers back.

No functional change.

Link: https://patch.msgid.link/20260710-work-binfmt_misc-locking-v3-16-a162f7cb58d6@kernel.org
Reviewed-by: Jori Koolstra <jkoolstra@xs4all.nl>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
This commit is contained in:
Christian Brauner
2026-07-10 11:33:17 +02:00
parent 0eec8a0428
commit 9eeca53dac
1 changed files with 20 additions and 18 deletions
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38
fs/binfmt_misc.c
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@@ -542,9 +542,17 @@ static struct binfmt_misc_entry *create_entry(const char __user *buffer,
return ERR_PTR(-EINVAL);
}
/* Commands accepted by the /status and /<entry> files. */
enum bm_command {
BM_CMD_IGNORE, /* empty write */
BM_CMD_DISABLE, /* "0" */
BM_CMD_ENABLE, /* "1" */
BM_CMD_REMOVE, /* "-1" */
};
/*
* Set status of entry/binfmt_misc:
* '1' enables, '0' disables and '-1' clears entry/binfmt_misc
* Parse what userspace wrote to /status or an entry file: '1' enables,
* '0' disables and '-1' removes the entry or all entries.
*/
static int parse_command(const char __user *buffer, size_t count)
{
@@ -555,15 +563,15 @@ static int parse_command(const char __user *buffer, size_t count)
if (copy_from_user(s, buffer, count))
return -EFAULT;
if (!count)
return 0;
return BM_CMD_IGNORE;
if (s[count - 1] == '\n')
count--;
if (count == 1 && s[0] == '0')
return 1;
return BM_CMD_DISABLE;
if (count == 1 && s[0] == '1')
return 2;
return BM_CMD_ENABLE;
if (count == 2 && s[0] == '-' && s[1] == '1')
return 3;
return BM_CMD_REMOVE;
return -EINVAL;
}
@@ -716,16 +724,13 @@ static ssize_t bm_entry_write(struct file *file, const char __user *buffer,
int res = parse_command(buffer, count);
switch (res) {
case 1:
/* Disable this handler. */
case BM_CMD_DISABLE:
clear_bit(MISC_FMT_ENABLED_BIT, &e->flags);
break;
case 2:
/* Enable this handler. */
case BM_CMD_ENABLE:
set_bit(MISC_FMT_ENABLED_BIT, &e->flags);
break;
case 3:
/* Delete this handler. */
case BM_CMD_REMOVE:
inode = d_inode(inode->i_sb->s_root);
inode_lock_nested(inode, I_MUTEX_PARENT);
@@ -865,16 +870,13 @@ static ssize_t bm_status_write(struct file *file, const char __user *buffer,
misc = i_binfmt_misc(file_inode(file));
switch (res) {
case 1:
/* Disable all handlers. */
case BM_CMD_DISABLE:
WRITE_ONCE(misc->enabled, false);
break;
case 2:
/* Enable all handlers. */
case BM_CMD_ENABLE:
WRITE_ONCE(misc->enabled, true);
break;
case 3:
/* Delete all handlers. */
case BM_CMD_REMOVE:
inode = d_inode(file_inode(file)->i_sb->s_root);
inode_lock_nested(inode, I_MUTEX_PARENT);