diff options
author | Tejun Heo <tj@kernel.org> | 2017-06-14 16:01:41 -0400 |
---|---|---|
committer | Tejun Heo <tj@kernel.org> | 2017-06-14 16:01:41 -0400 |
commit | b6053d40e3387c916d56d319ba6bfdb2c42a67c7 (patch) | |
tree | 5f45453c0f4675950f56ee4ef1fdb16057eb6552 /kernel | |
parent | 2866c0b4cf25274040f0b4cc045ad1f44b885dd8 (diff) | |
download | linux-stable-b6053d40e3387c916d56d319ba6bfdb2c42a67c7.tar.gz linux-stable-b6053d40e3387c916d56d319ba6bfdb2c42a67c7.tar.bz2 linux-stable-b6053d40e3387c916d56d319ba6bfdb2c42a67c7.zip |
cgroup: fix lockdep warning in debug controller
The debug controller grabs cgroup_mutex from interface file show
functions which can deadlock and triggers lockdep warnings. Fix it by
using cgroup_kn_lock_live()/cgroup_kn_unlock() instead.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Waiman Long <longman@redhat.com>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/cgroup/debug.c | 29 |
1 files changed, 21 insertions, 8 deletions
diff --git a/kernel/cgroup/debug.c b/kernel/cgroup/debug.c index 163fdbd7adf6..dac46af22782 100644 --- a/kernel/cgroup/debug.c +++ b/kernel/cgroup/debug.c @@ -38,12 +38,15 @@ static u64 debug_taskcount_read(struct cgroup_subsys_state *css, static int current_css_set_read(struct seq_file *seq, void *v) { + struct kernfs_open_file *of = seq->private; struct css_set *cset; struct cgroup_subsys *ss; struct cgroup_subsys_state *css; int i, refcnt; - mutex_lock(&cgroup_mutex); + if (!cgroup_kn_lock_live(of->kn, false)) + return -ENODEV; + spin_lock_irq(&css_set_lock); rcu_read_lock(); cset = rcu_dereference(current->cgroups); @@ -65,7 +68,7 @@ static int current_css_set_read(struct seq_file *seq, void *v) } rcu_read_unlock(); spin_unlock_irq(&css_set_lock); - mutex_unlock(&cgroup_mutex); + cgroup_kn_unlock(of->kn); return 0; } @@ -174,13 +177,17 @@ static int cgroup_css_links_read(struct seq_file *seq, void *v) static int cgroup_subsys_states_read(struct seq_file *seq, void *v) { - struct cgroup *cgrp = seq_css(seq)->cgroup; + struct kernfs_open_file *of = seq->private; + struct cgroup *cgrp; struct cgroup_subsys *ss; struct cgroup_subsys_state *css; char pbuf[16]; int i; - mutex_lock(&cgroup_mutex); + cgrp = cgroup_kn_lock_live(of->kn, false); + if (!cgrp) + return -ENODEV; + for_each_subsys(ss, i) { css = rcu_dereference_check(cgrp->subsys[ss->id], true); if (!css) @@ -196,7 +203,8 @@ static int cgroup_subsys_states_read(struct seq_file *seq, void *v) (unsigned long)css, css->id, atomic_read(&css->online_cnt), pbuf); } - mutex_unlock(&cgroup_mutex); + + cgroup_kn_unlock(of->kn); return 0; } @@ -221,12 +229,17 @@ static void cgroup_masks_read_one(struct seq_file *seq, const char *name, static int cgroup_masks_read(struct seq_file *seq, void *v) { - struct cgroup *cgrp = seq_css(seq)->cgroup; + struct kernfs_open_file *of = seq->private; + struct cgroup *cgrp; + + cgrp = cgroup_kn_lock_live(of->kn, false); + if (!cgrp) + return -ENODEV; - mutex_lock(&cgroup_mutex); cgroup_masks_read_one(seq, "subtree_control", cgrp->subtree_control); cgroup_masks_read_one(seq, "subtree_ss_mask", cgrp->subtree_ss_mask); - mutex_unlock(&cgroup_mutex); + + cgroup_kn_unlock(of->kn); return 0; } |