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memcg_write_event_control(): switch to CLASS(fd)

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some reordering required - take both fdget() to the point before
the allocations, with matching move of fdput() to the very end
of failure exit(s); after that it converts trivially.

simplify the cleanups that involve css_put(), while we are at it...

Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2024-07-22 20:18:10 -04:00
parent 66635b0776
commit 7133dd5ac6
1 changed files with 15 additions and 29 deletions
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44
mm/memcontrol-v1.c
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@ -1911,8 +1911,6 @@ static ssize_t memcg_write_event_control(struct kernfs_open_file *of,
struct mem_cgroup_event *event;
struct cgroup_subsys_state *cfile_css;
unsigned int efd, cfd;
struct fd efile;
struct fd cfile;
struct dentry *cdentry;
const char *name;
char *endp;
@ -1936,6 +1934,12 @@ static ssize_t memcg_write_event_control(struct kernfs_open_file *of,
else
return -EINVAL;
CLASS(fd, efile)(efd);
if (fd_empty(efile))
return -EBADF;
CLASS(fd, cfile)(cfd);
event = kzalloc(sizeof(*event), GFP_KERNEL);
if (!event)
return -ENOMEM;
@ -1946,20 +1950,13 @@ static ssize_t memcg_write_event_control(struct kernfs_open_file *of,
init_waitqueue_func_entry(&event->wait, memcg_event_wake);
INIT_WORK(&event->remove, memcg_event_remove);
efile = fdget(efd);
if (!fd_file(efile)) {
ret = -EBADF;
goto out_kfree;
}
event->eventfd = eventfd_ctx_fileget(fd_file(efile));
if (IS_ERR(event->eventfd)) {
ret = PTR_ERR(event->eventfd);
goto out_put_efile;
goto out_kfree;
}
cfile = fdget(cfd);
if (!fd_file(cfile)) {
if (fd_empty(cfile)) {
ret = -EBADF;
goto out_put_eventfd;
}
@ -1968,7 +1965,7 @@ static ssize_t memcg_write_event_control(struct kernfs_open_file *of,
/* AV: shouldn't we check that it's been opened for read instead? */
ret = file_permission(fd_file(cfile), MAY_READ);
if (ret < 0)
goto out_put_cfile;
goto out_put_eventfd;
/*
* The control file must be a regular cgroup1 file. As a regular cgroup
@ -1977,7 +1974,7 @@ static ssize_t memcg_write_event_control(struct kernfs_open_file *of,
cdentry = fd_file(cfile)->f_path.dentry;
if (cdentry->d_sb->s_type != &cgroup_fs_type || !d_is_reg(cdentry)) {
ret = -EINVAL;
goto out_put_cfile;
goto out_put_eventfd;
}
/*
@ -2010,7 +2007,7 @@ static ssize_t memcg_write_event_control(struct kernfs_open_file *of,
event->unregister_event = memsw_cgroup_usage_unregister_event;
} else {
ret = -EINVAL;
goto out_put_cfile;
goto out_put_eventfd;
}
/*
@ -2022,11 +2019,9 @@ static ssize_t memcg_write_event_control(struct kernfs_open_file *of,
&memory_cgrp_subsys);
ret = -EINVAL;
if (IS_ERR(cfile_css))
goto out_put_cfile;
if (cfile_css != css) {
css_put(cfile_css);
goto out_put_cfile;
}
goto out_put_eventfd;
if (cfile_css != css)
goto out_put_css;
ret = event->register_event(memcg, event->eventfd, buf);
if (ret)
@ -2037,23 +2032,14 @@ static ssize_t memcg_write_event_control(struct kernfs_open_file *of,
spin_lock_irq(&memcg->event_list_lock);
list_add(&event->list, &memcg->event_list);
spin_unlock_irq(&memcg->event_list_lock);
fdput(cfile);
fdput(efile);
return nbytes;
out_put_css:
css_put(css);
out_put_cfile:
fdput(cfile);
css_put(cfile_css);
out_put_eventfd:
eventfd_ctx_put(event->eventfd);
out_put_efile:
fdput(efile);
out_kfree:
kfree(event);
return ret;
}