cgroup: replace cftype->read_seq_string() with cftype->seq_show()

In preparation of conversion to kernfs, cgroup file handling is
updated so that it can be easily mapped to kernfs.  This patch
replaces cftype->read_seq_string() with cftype->seq_show() which is
not limited to single_open() operation and will map directcly to
kernfs seq_file interface.

The conversions are mechanical.  As ->seq_show() doesn't have @css and
@cft, the functions which make use of them are converted to use
seq_css() and seq_cft() respectively.  In several occassions, e.f. if
it has seq_string in its name, the function name is updated to fit the
new method better.

This patch does not introduce any behavior changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Aristeu Rozanski <arozansk@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Neil Horman <nhorman@tuxdriver.com>

5 files changed, 33 insertions, 41 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 036c05d8e572..c45e63328a0a 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2212,10 +2212,9 @@ static int cgroup_release_agent_write(struct cgroup_subsys_state *css,
         return 0;
 }
 
-static int cgroup_release_agent_show(struct cgroup_subsys_state *css,
-                                     struct cftype *cft, struct seq_file *seq)
+static int cgroup_release_agent_show(struct seq_file *seq, void *v)
 {
-        struct cgroup *cgrp = css->cgroup;
+        struct cgroup *cgrp = seq_css(seq)->cgroup;
 
         if (!cgroup_lock_live_group(cgrp))
                 return -ENODEV;
@@ -2225,10 +2224,11 @@ static int cgroup_release_agent_show(struct cgroup_subsys_state *css,
         return 0;
 }
 
-static int cgroup_sane_behavior_show(struct cgroup_subsys_state *css,
-                                     struct cftype *cft, struct seq_file *seq)
+static int cgroup_sane_behavior_show(struct seq_file *seq, void *v)
 {
-        seq_printf(seq, "%d\n", cgroup_sane_behavior(css->cgroup));
+        struct cgroup *cgrp = seq_css(seq)->cgroup;
+
+        seq_printf(seq, "%d\n", cgroup_sane_behavior(cgrp));
         return 0;
 }
 
@@ -2291,8 +2291,8 @@ static int cgroup_seqfile_show(struct seq_file *m, void *arg)
         struct cftype *cft = seq_cft(m);
         struct cgroup_subsys_state *css = seq_css(m);
 
-        if (cft->read_seq_string)
-                return cft->read_seq_string(css, cft, m);
+        if (cft->seq_show)
+                return cft->seq_show(m, arg);
 
         if (cft->read_u64)
                 seq_printf(m, "%llu\n", cft->read_u64(css, cft));
@@ -2559,7 +2559,7 @@ static umode_t cgroup_file_mode(const struct cftype *cft)
         if (cft->mode)
                 return cft->mode;
 
-        if (cft->read_u64 || cft->read_s64 || cft->read_seq_string)
+        if (cft->read_u64 || cft->read_s64 || cft->seq_show)
                 mode |= S_IRUGO;
 
         if (cft->write_u64 || cft->write_s64 || cft->write_string ||
@@ -3874,7 +3874,7 @@ static struct cftype cgroup_base_files[] = {
         {
                 .name = "cgroup.sane_behavior",
                 .flags = CFTYPE_ONLY_ON_ROOT,
-                .read_seq_string = cgroup_sane_behavior_show,
+                .seq_show = cgroup_sane_behavior_show,
         },
 
         /*
@@ -3899,7 +3899,7 @@ static struct cftype cgroup_base_files[] = {
         {
                 .name = "release_agent",
                 .flags = CFTYPE_INSANE | CFTYPE_ONLY_ON_ROOT,
-                .read_seq_string = cgroup_release_agent_show,
+                .seq_show = cgroup_release_agent_show,
                 .write_string = cgroup_release_agent_write,
                 .max_write_len = PATH_MAX,
         },
@@ -5274,9 +5274,7 @@ static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css,
         return count;
 }
 
-static int current_css_set_cg_links_read(struct cgroup_subsys_state *css,
-                                         struct cftype *cft,
-                                         struct seq_file *seq)
+static int current_css_set_cg_links_read(struct seq_file *seq, void *v)
 {
         struct cgrp_cset_link *link;
         struct css_set *cset;
@@ -5301,9 +5299,9 @@ static int current_css_set_cg_links_read(struct cgroup_subsys_state *css,
 }
 
 #define MAX_TASKS_SHOWN_PER_CSS 25
-static int cgroup_css_links_read(struct cgroup_subsys_state *css,
-                                 struct cftype *cft, struct seq_file *seq)
+static int cgroup_css_links_read(struct seq_file *seq, void *v)
 {
+        struct cgroup_subsys_state *css = seq_css(seq);
         struct cgrp_cset_link *link;
 
         read_lock(&css_set_lock);
@@ -5349,12 +5347,12 @@ static struct cftype debug_files[] =  {
 
         {
                 .name = "current_css_set_cg_links",
-                .read_seq_string = current_css_set_cg_links_read,
+                .seq_show = current_css_set_cg_links_read,
         },
 
         {
                 .name = "cgroup_css_links",
-                .read_seq_string = cgroup_css_links_read,
+                .seq_show = cgroup_css_links_read,
         },
 
         {
diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
index f0ff64d0ebaa..6c3154e477f6 100644
--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -301,10 +301,9 @@ out_unlock:
         spin_unlock_irq(&freezer->lock);
 }
 
-static int freezer_read(struct cgroup_subsys_state *css, struct cftype *cft,
-                        struct seq_file *m)
+static int freezer_read(struct seq_file *m, void *v)
 {
-        struct cgroup_subsys_state *pos;
+        struct cgroup_subsys_state *css = seq_css(m), *pos;
 
         rcu_read_lock();
 
@@ -458,7 +457,7 @@ static struct cftype files[] = {
         {
                 .name = "state",
                 .flags = CFTYPE_NOT_ON_ROOT,
-                .read_seq_string = freezer_read,
+                .seq_show = freezer_read,
                 .write_string = freezer_write,
         },
         {
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 032929f91648..4410ac6a55f1 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -1732,12 +1732,10 @@ out_unlock:
  * and since these maps can change value dynamically, one could read
  * gibberish by doing partial reads while a list was changing.
  */
-static int cpuset_common_read_seq_string(struct cgroup_subsys_state *css,
-                                         struct cftype *cft,
-                                         struct seq_file *sf)
+static int cpuset_common_seq_show(struct seq_file *sf, void *v)
 {
-        struct cpuset *cs = css_cs(css);
-        cpuset_filetype_t type = cft->private;
+        struct cpuset *cs = css_cs(seq_css(sf));
+        cpuset_filetype_t type = seq_cft(sf)->private;
         ssize_t count;
         char *buf, *s;
         int ret = 0;
@@ -1824,7 +1822,7 @@ static s64 cpuset_read_s64(struct cgroup_subsys_state *css, struct cftype *cft)
 static struct cftype files[] = {
         {
                 .name = "cpus",
-                .read_seq_string = cpuset_common_read_seq_string,
+                .seq_show = cpuset_common_seq_show,
                 .write_string = cpuset_write_resmask,
                 .max_write_len = (100U + 6 * NR_CPUS),
                 .private = FILE_CPULIST,
@@ -1832,7 +1830,7 @@ static struct cftype files[] = {
 
         {
                 .name = "mems",
-                .read_seq_string = cpuset_common_read_seq_string,
+                .seq_show = cpuset_common_seq_show,
                 .write_string = cpuset_write_resmask,
                 .max_write_len = (100U + 6 * MAX_NUMNODES),
                 .private = FILE_MEMLIST,
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index f28ec6722f0b..7e8cbb9ee4d6 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7256,10 +7256,9 @@ static int __cfs_schedulable(struct task_group *tg, u64 period, u64 quota)
         return ret;
 }
 
-static int cpu_stats_show(struct cgroup_subsys_state *css, struct cftype *cft,
-                          struct seq_file *sf)
+static int cpu_stats_show(struct seq_file *sf, void *v)
 {
-        struct task_group *tg = css_tg(css);
+        struct task_group *tg = css_tg(seq_css(sf));
         struct cfs_bandwidth *cfs_b = &tg->cfs_bandwidth;
 
         seq_printf(sf, "nr_periods %d\n", cfs_b->nr_periods);
@@ -7318,7 +7317,7 @@ static struct cftype cpu_files[] = {
         },
         {
                 .name = "stat",
-                .read_seq_string = cpu_stats_show,
+                .seq_show = cpu_stats_show,
         },
 #endif
 #ifdef CONFIG_RT_GROUP_SCHED
diff --git a/kernel/sched/cpuacct.c b/kernel/sched/cpuacct.c
index dd88738cd4a9..622e0818f905 100644
--- a/kernel/sched/cpuacct.c
+++ b/kernel/sched/cpuacct.c
@@ -163,10 +163,9 @@ out:
         return err;
 }
 
-static int cpuacct_percpu_seq_read(struct cgroup_subsys_state *css,
-                                   struct cftype *cft, struct seq_file *m)
+static int cpuacct_percpu_seq_show(struct seq_file *m, void *V)
 {
-        struct cpuacct *ca = css_ca(css);
+        struct cpuacct *ca = css_ca(seq_css(m));
         u64 percpu;
         int i;
 
@@ -183,10 +182,9 @@ static const char * const cpuacct_stat_desc[] = {
         [CPUACCT_STAT_SYSTEM] = "system",
 };
 
-static int cpuacct_stats_show(struct cgroup_subsys_state *css,
-                              struct cftype *cft, struct seq_file *sf)
+static int cpuacct_stats_show(struct seq_file *sf, void *v)
 {
-        struct cpuacct *ca = css_ca(css);
+        struct cpuacct *ca = css_ca(seq_css(sf));
         int cpu;
         s64 val = 0;
 
@@ -220,11 +218,11 @@ static struct cftype files[] = {
         },
         {
                 .name = "usage_percpu",
-                .read_seq_string = cpuacct_percpu_seq_read,
+                .seq_show = cpuacct_percpu_seq_show,
         },
         {
                 .name = "stat",
-                .read_seq_string = cpuacct_stats_show,
+                .seq_show = cpuacct_stats_show,
         },
         { }     /* terminate */
 };