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| author | Tejun Heo <tj@kernel.org> | 2014-09-24 13:31:50 -0400 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2014-09-24 13:31:50 -0400 |
| commit | 2aad2a86f6685c10360ec8a5a55eb9ab7059cb72 (patch) | |
| tree | 85da25f36ba0c8158becdc8ba940201652cf30ce /kernel/cgroup.c | |
| parent | f47ad45784611297b699f3dffb6c7222b76afe64 (diff) | |
| download | linux-rt-2aad2a86f6685c10360ec8a5a55eb9ab7059cb72.tar.gz | |
percpu_ref: add PERCPU_REF_INIT_* flags
With the recent addition of percpu_ref_reinit(), percpu_ref now can be
used as a persistent switch which can be turned on and off repeatedly
where turning off maps to killing the ref and waiting for it to drain;
however, there currently isn't a way to initialize a percpu_ref in its
off (killed and drained) state, which can be inconvenient for certain
persistent switch use cases.
Similarly, percpu_ref_switch_to_atomic/percpu() allow dynamic
selection of operation mode; however, currently a newly initialized
percpu_ref is always in percpu mode making it impossible to avoid the
latency overhead of switching to atomic mode.
This patch adds @flags to percpu_ref_init() and implements the
following flags.
* PERCPU_REF_INIT_ATOMIC : start ref in atomic mode
* PERCPU_REF_INIT_DEAD : start ref killed and drained
These flags should be able to serve the above two use cases.
v2: target_core_tpg.c conversion was missing. Fixed.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Kent Overstreet <kmo@daterainc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Diffstat (limited to 'kernel/cgroup.c')
| -rw-r--r-- | kernel/cgroup.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index a99d504294de..753df01a9831 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -1634,7 +1634,8 @@ static int cgroup_setup_root(struct cgroup_root *root, unsigned int ss_mask) goto out; root_cgrp->id = ret; - ret = percpu_ref_init(&root_cgrp->self.refcnt, css_release, GFP_KERNEL); + ret = percpu_ref_init(&root_cgrp->self.refcnt, css_release, 0, + GFP_KERNEL); if (ret) goto out; @@ -4510,7 +4511,7 @@ static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss, init_and_link_css(css, ss, cgrp); - err = percpu_ref_init(&css->refcnt, css_release, GFP_KERNEL); + err = percpu_ref_init(&css->refcnt, css_release, 0, GFP_KERNEL); if (err) goto err_free_css; @@ -4583,7 +4584,7 @@ static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, goto out_unlock; } - ret = percpu_ref_init(&cgrp->self.refcnt, css_release, GFP_KERNEL); + ret = percpu_ref_init(&cgrp->self.refcnt, css_release, 0, GFP_KERNEL); if (ret) goto out_free_cgrp; |