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authorLinus Torvalds <torvalds@linux-foundation.org>2022-10-17 18:52:43 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2022-10-17 18:52:43 -0700
commitbb1a1146467ad812bb65440696df0782e2bc63c8 (patch)
tree3f8cbc06bc26b8bebfcd8ddbbb70e246fd5d2bf8 /kernel
parentbbb8ceb5e2421184db9560e9d2cfaf858e1db616 (diff)
parent79a818b5087393d5a4cb356d4545d02f55bf1a2f (diff)
Merge tag 'cgroup-for-6.1-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fixes from Tejun Heo: - Fix a recent regression where a sleeping kernfs function is called with css_set_lock (spinlock) held - Revert the commit to enable cgroup1 support for cgroup_get_from_fd/file() Multiple users assume that the lookup only works for cgroup2 and breaks when fed a cgroup1 file. Instead, introduce a separate set of functions to lookup both v1 and v2 and use them where the user explicitly wants to support both versions. - Compat update for tools/perf/util/bpf_skel/bperf_cgroup.bpf.c. - Add Josef Bacik as a blkcg maintainer. * tag 'cgroup-for-6.1-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: blkcg: Update MAINTAINERS entry mm: cgroup: fix comments for get from fd/file helpers perf stat: Support old kernels for bperf cgroup counting bpf: cgroup_iter: support cgroup1 using cgroup fd cgroup: add cgroup_v1v2_get_from_[fd/file]() Revert "cgroup: enable cgroup_get_from_file() on cgroup1" cgroup: Reorganize css_set_lock and kernfs path processing
Diffstat (limited to 'kernel')
-rw-r--r--kernel/bpf/cgroup_iter.c2
-rw-r--r--kernel/cgroup/cgroup.c99
2 files changed, 80 insertions, 21 deletions
diff --git a/kernel/bpf/cgroup_iter.c b/kernel/bpf/cgroup_iter.c
index 0d200a993489..9fcf09f2ef00 100644
--- a/kernel/bpf/cgroup_iter.c
+++ b/kernel/bpf/cgroup_iter.c
@@ -196,7 +196,7 @@ static int bpf_iter_attach_cgroup(struct bpf_prog *prog,
return -EINVAL;
if (fd)
- cgrp = cgroup_get_from_fd(fd);
+ cgrp = cgroup_v1v2_get_from_fd(fd);
else if (id)
cgrp = cgroup_get_from_id(id);
else /* walk the entire hierarchy by default. */
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 7f486677ab1f..2319946715e0 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -1392,6 +1392,9 @@ static void cgroup_destroy_root(struct cgroup_root *root)
cgroup_free_root(root);
}
+/*
+ * Returned cgroup is without refcount but it's valid as long as cset pins it.
+ */
static inline struct cgroup *__cset_cgroup_from_root(struct css_set *cset,
struct cgroup_root *root)
{
@@ -1403,6 +1406,7 @@ static inline struct cgroup *__cset_cgroup_from_root(struct css_set *cset,
res_cgroup = cset->dfl_cgrp;
} else {
struct cgrp_cset_link *link;
+ lockdep_assert_held(&css_set_lock);
list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
struct cgroup *c = link->cgrp;
@@ -1414,6 +1418,7 @@ static inline struct cgroup *__cset_cgroup_from_root(struct css_set *cset,
}
}
+ BUG_ON(!res_cgroup);
return res_cgroup;
}
@@ -1436,23 +1441,36 @@ current_cgns_cgroup_from_root(struct cgroup_root *root)
rcu_read_unlock();
- BUG_ON(!res);
return res;
}
+/*
+ * Look up cgroup associated with current task's cgroup namespace on the default
+ * hierarchy.
+ *
+ * Unlike current_cgns_cgroup_from_root(), this doesn't need locks:
+ * - Internal rcu_read_lock is unnecessary because we don't dereference any rcu
+ * pointers.
+ * - css_set_lock is not needed because we just read cset->dfl_cgrp.
+ * - As a bonus returned cgrp is pinned with the current because it cannot
+ * switch cgroup_ns asynchronously.
+ */
+static struct cgroup *current_cgns_cgroup_dfl(void)
+{
+ struct css_set *cset;
+
+ cset = current->nsproxy->cgroup_ns->root_cset;
+ return __cset_cgroup_from_root(cset, &cgrp_dfl_root);
+}
+
/* look up cgroup associated with given css_set on the specified hierarchy */
static struct cgroup *cset_cgroup_from_root(struct css_set *cset,
struct cgroup_root *root)
{
- struct cgroup *res = NULL;
-
lockdep_assert_held(&cgroup_mutex);
lockdep_assert_held(&css_set_lock);
- res = __cset_cgroup_from_root(cset, root);
-
- BUG_ON(!res);
- return res;
+ return __cset_cgroup_from_root(cset, root);
}
/*
@@ -6191,9 +6209,7 @@ struct cgroup *cgroup_get_from_id(u64 id)
if (!cgrp)
return ERR_PTR(-ENOENT);
- spin_lock_irq(&css_set_lock);
- root_cgrp = current_cgns_cgroup_from_root(&cgrp_dfl_root);
- spin_unlock_irq(&css_set_lock);
+ root_cgrp = current_cgns_cgroup_dfl();
if (!cgroup_is_descendant(cgrp, root_cgrp)) {
cgroup_put(cgrp);
return ERR_PTR(-ENOENT);
@@ -6294,16 +6310,42 @@ void cgroup_fork(struct task_struct *child)
INIT_LIST_HEAD(&child->cg_list);
}
-static struct cgroup *cgroup_get_from_file(struct file *f)
+/**
+ * cgroup_v1v2_get_from_file - get a cgroup pointer from a file pointer
+ * @f: file corresponding to cgroup_dir
+ *
+ * Find the cgroup from a file pointer associated with a cgroup directory.
+ * Returns a pointer to the cgroup on success. ERR_PTR is returned if the
+ * cgroup cannot be found.
+ */
+static struct cgroup *cgroup_v1v2_get_from_file(struct file *f)
{
struct cgroup_subsys_state *css;
- struct cgroup *cgrp;
css = css_tryget_online_from_dir(f->f_path.dentry, NULL);
if (IS_ERR(css))
return ERR_CAST(css);
- cgrp = css->cgroup;
+ return css->cgroup;
+}
+
+/**
+ * cgroup_get_from_file - same as cgroup_v1v2_get_from_file, but only supports
+ * cgroup2.
+ * @f: file corresponding to cgroup2_dir
+ */
+static struct cgroup *cgroup_get_from_file(struct file *f)
+{
+ struct cgroup *cgrp = cgroup_v1v2_get_from_file(f);
+
+ if (IS_ERR(cgrp))
+ return ERR_CAST(cgrp);
+
+ if (!cgroup_on_dfl(cgrp)) {
+ cgroup_put(cgrp);
+ return ERR_PTR(-EBADF);
+ }
+
return cgrp;
}
@@ -6772,10 +6814,8 @@ struct cgroup *cgroup_get_from_path(const char *path)
struct cgroup *cgrp = ERR_PTR(-ENOENT);
struct cgroup *root_cgrp;
- spin_lock_irq(&css_set_lock);
- root_cgrp = current_cgns_cgroup_from_root(&cgrp_dfl_root);
+ root_cgrp = current_cgns_cgroup_dfl();
kn = kernfs_walk_and_get(root_cgrp->kn, path);
- spin_unlock_irq(&css_set_lock);
if (!kn)
goto out;
@@ -6800,15 +6840,15 @@ out:
EXPORT_SYMBOL_GPL(cgroup_get_from_path);
/**
- * cgroup_get_from_fd - get a cgroup pointer from a fd
- * @fd: fd obtained by open(cgroup2_dir)
+ * cgroup_v1v2_get_from_fd - get a cgroup pointer from a fd
+ * @fd: fd obtained by open(cgroup_dir)
*
* Find the cgroup from a fd which should be obtained
* by opening a cgroup directory. Returns a pointer to the
* cgroup on success. ERR_PTR is returned if the cgroup
* cannot be found.
*/
-struct cgroup *cgroup_get_from_fd(int fd)
+struct cgroup *cgroup_v1v2_get_from_fd(int fd)
{
struct cgroup *cgrp;
struct file *f;
@@ -6817,10 +6857,29 @@ struct cgroup *cgroup_get_from_fd(int fd)
if (!f)
return ERR_PTR(-EBADF);
- cgrp = cgroup_get_from_file(f);
+ cgrp = cgroup_v1v2_get_from_file(f);
fput(f);
return cgrp;
}
+
+/**
+ * cgroup_get_from_fd - same as cgroup_v1v2_get_from_fd, but only supports
+ * cgroup2.
+ * @fd: fd obtained by open(cgroup2_dir)
+ */
+struct cgroup *cgroup_get_from_fd(int fd)
+{
+ struct cgroup *cgrp = cgroup_v1v2_get_from_fd(fd);
+
+ if (IS_ERR(cgrp))
+ return ERR_CAST(cgrp);
+
+ if (!cgroup_on_dfl(cgrp)) {
+ cgroup_put(cgrp);
+ return ERR_PTR(-EBADF);
+ }
+ return cgrp;
+}
EXPORT_SYMBOL_GPL(cgroup_get_from_fd);
static u64 power_of_ten(int power)