[RFC][PATCH 7/7] CGroup API: Update cpusets to use cgroup structured file API

[Paul Menage <menage@google.com>]

[-- Attachment #1: cpuset_files.patch --]
[-- Type: text/plain, Size: 7756 bytes --]

Many of the cpusets control files are simple integer values, which
don't require the overhead of memory allocations for reads and writes.

Move the handlers for these control files into cpuset_read_uint() and
cpuset_write_uint(). This also has the advantage that the control
files show up as "u64" rather than "string" in the cgroup.api file.

Signed-off-by: Paul Menage <menage@google.com>

---
 kernel/cpuset.c |  158 +++++++++++++++++++++++++++++---------------------------
 1 file changed, 83 insertions(+), 75 deletions(-)

Index: cgroupmap-2.6.24-mm1/kernel/cpuset.c
===================================================================
--- cgroupmap-2.6.24-mm1.orig/kernel/cpuset.c
+++ cgroupmap-2.6.24-mm1/kernel/cpuset.c
@@ -999,19 +999,6 @@ int current_cpuset_is_being_rebound(void
 }
 
 /*
- * Call with cgroup_mutex held.
- */
-
-static int update_memory_pressure_enabled(struct cpuset *cs, char *buf)
-{
-	if (simple_strtoul(buf, NULL, 10) != 0)
-		cpuset_memory_pressure_enabled = 1;
-	else
-		cpuset_memory_pressure_enabled = 0;
-	return 0;
-}
-
-/*
  * update_flag - read a 0 or a 1 in a file and update associated flag
  * bit:	the bit to update (CS_CPU_EXCLUSIVE, CS_MEM_EXCLUSIVE,
  *				CS_SCHED_LOAD_BALANCE,
@@ -1023,15 +1010,13 @@ static int update_memory_pressure_enable
  * Call with cgroup_mutex held.
  */
 
-static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, char *buf)
+static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
+		       int turning_on)
 {
-	int turning_on;
 	struct cpuset trialcs;
 	int err;
 	int cpus_nonempty, balance_flag_changed;
 
-	turning_on = (simple_strtoul(buf, NULL, 10) != 0);
-
 	trialcs = *cs;
 	if (turning_on)
 		set_bit(bit, &trialcs.flags);
@@ -1247,44 +1232,66 @@ static ssize_t cpuset_common_file_write(
 	case FILE_MEMLIST:
 		retval = update_nodemask(cs, buffer);
 		break;
+	default:
+		retval = -EINVAL;
+		goto out2;
+	}
+
+	if (retval == 0)
+		retval = nbytes;
+out2:
+	cgroup_unlock();
+out1:
+	kfree(buffer);
+	return retval;
+}
+
+static int cpuset_write_uint(struct cgroup *cgrp, struct cftype *cft, u64 val)
+{
+	int retval = 0;
+	struct cpuset *cs = cgroup_cs(cgrp);
+	cpuset_filetype_t type = cft->private;
+
+	cgroup_lock();
+
+	if (cgroup_is_removed(cgrp)) {
+		cgroup_unlock();
+		return -ENODEV;
+	}
+
+	switch (type) {
 	case FILE_CPU_EXCLUSIVE:
-		retval = update_flag(CS_CPU_EXCLUSIVE, cs, buffer);
+		retval = update_flag(CS_CPU_EXCLUSIVE, cs, val);
 		break;
 	case FILE_MEM_EXCLUSIVE:
-		retval = update_flag(CS_MEM_EXCLUSIVE, cs, buffer);
+		retval = update_flag(CS_MEM_EXCLUSIVE, cs, val);
 		break;
 	case FILE_SCHED_LOAD_BALANCE:
-		retval = update_flag(CS_SCHED_LOAD_BALANCE, cs, buffer);
+		retval = update_flag(CS_SCHED_LOAD_BALANCE, cs, val);
 		break;
 	case FILE_MEMORY_MIGRATE:
-		retval = update_flag(CS_MEMORY_MIGRATE, cs, buffer);
+		retval = update_flag(CS_MEMORY_MIGRATE, cs, val);
 		break;
 	case FILE_MEMORY_PRESSURE_ENABLED:
-		retval = update_memory_pressure_enabled(cs, buffer);
+		cpuset_memory_pressure_enabled = val;
 		break;
 	case FILE_MEMORY_PRESSURE:
 		retval = -EACCES;
 		break;
 	case FILE_SPREAD_PAGE:
-		retval = update_flag(CS_SPREAD_PAGE, cs, buffer);
+		retval = update_flag(CS_SPREAD_PAGE, cs, val);
 		cs->mems_generation = cpuset_mems_generation++;
 		break;
 	case FILE_SPREAD_SLAB:
-		retval = update_flag(CS_SPREAD_SLAB, cs, buffer);
+		retval = update_flag(CS_SPREAD_SLAB, cs, val);
 		cs->mems_generation = cpuset_mems_generation++;
 		break;
 	default:
 		retval = -EINVAL;
-		goto out2;
+		break;
 	}
-
-	if (retval == 0)
-		retval = nbytes;
-out2:
 	cgroup_unlock();
-out1:
-	kfree(buffer);
-	return retval;
+	return -EINVAL;
 }
 
 /*
@@ -1345,30 +1352,6 @@ static ssize_t cpuset_common_file_read(s
 	case FILE_MEMLIST:
 		s += cpuset_sprintf_memlist(s, cs);
 		break;
-	case FILE_CPU_EXCLUSIVE:
-		*s++ = is_cpu_exclusive(cs) ? '1' : '0';
-		break;
-	case FILE_MEM_EXCLUSIVE:
-		*s++ = is_mem_exclusive(cs) ? '1' : '0';
-		break;
-	case FILE_SCHED_LOAD_BALANCE:
-		*s++ = is_sched_load_balance(cs) ? '1' : '0';
-		break;
-	case FILE_MEMORY_MIGRATE:
-		*s++ = is_memory_migrate(cs) ? '1' : '0';
-		break;
-	case FILE_MEMORY_PRESSURE_ENABLED:
-		*s++ = cpuset_memory_pressure_enabled ? '1' : '0';
-		break;
-	case FILE_MEMORY_PRESSURE:
-		s += sprintf(s, "%d", fmeter_getrate(&cs->fmeter));
-		break;
-	case FILE_SPREAD_PAGE:
-		*s++ = is_spread_page(cs) ? '1' : '0';
-		break;
-	case FILE_SPREAD_SLAB:
-		*s++ = is_spread_slab(cs) ? '1' : '0';
-		break;
 	default:
 		retval = -EINVAL;
 		goto out;
@@ -1381,8 +1364,32 @@ out:
 	return retval;
 }
 
-
-
+static u64 cpuset_read_uint(struct cgroup *cont, struct cftype *cft)
+{
+	struct cpuset *cs = cgroup_cs(cont);
+	cpuset_filetype_t type = cft->private;
+	switch (type) {
+	case FILE_CPU_EXCLUSIVE:
+		return is_cpu_exclusive(cs);
+	case FILE_MEM_EXCLUSIVE:
+		return is_mem_exclusive(cs);
+	case FILE_SCHED_LOAD_BALANCE:
+		return is_sched_load_balance(cs);
+	case FILE_MEMORY_MIGRATE:
+		return is_memory_migrate(cs);
+	case FILE_MEMORY_PRESSURE_ENABLED:
+		return cpuset_memory_pressure_enabled;
+	case FILE_MEMORY_PRESSURE:
+		return fmeter_getrate(&cs->fmeter);
+		break;
+	case FILE_SPREAD_PAGE:
+		return is_spread_page(cs);
+	case FILE_SPREAD_SLAB:
+		return is_spread_slab(cs);
+	default:
+		BUG();
+	}
+}
 
 
 /*
@@ -1405,57 +1412,58 @@ static struct cftype cft_mems = {
 
 static struct cftype cft_cpu_exclusive = {
 	.name = "cpu_exclusive",
-	.read = cpuset_common_file_read,
-	.write = cpuset_common_file_write,
+	.read_uint = cpuset_read_uint,
+	.write_uint = cpuset_write_uint,
 	.private = FILE_CPU_EXCLUSIVE,
 };
 
 static struct cftype cft_mem_exclusive = {
 	.name = "mem_exclusive",
-	.read = cpuset_common_file_read,
-	.write = cpuset_common_file_write,
+	.read_uint = cpuset_read_uint,
+	.write_uint = cpuset_write_uint,
 	.private = FILE_MEM_EXCLUSIVE,
 };
 
 static struct cftype cft_sched_load_balance = {
 	.name = "sched_load_balance",
-	.read = cpuset_common_file_read,
-	.write = cpuset_common_file_write,
+	.read_uint = cpuset_read_uint,
+	.write_uint = cpuset_write_uint,
 	.private = FILE_SCHED_LOAD_BALANCE,
 };
 
 static struct cftype cft_memory_migrate = {
 	.name = "memory_migrate",
-	.read = cpuset_common_file_read,
-	.write = cpuset_common_file_write,
+	.read_uint = cpuset_read_uint,
+	.read_uint = cpuset_read_uint,
+	.write_uint = cpuset_write_uint,
 	.private = FILE_MEMORY_MIGRATE,
 };
 
 static struct cftype cft_memory_pressure_enabled = {
 	.name = "memory_pressure_enabled",
-	.read = cpuset_common_file_read,
-	.write = cpuset_common_file_write,
+	.read_uint = cpuset_read_uint,
+	.write_uint = cpuset_write_uint,
 	.private = FILE_MEMORY_PRESSURE_ENABLED,
 };
 
 static struct cftype cft_memory_pressure = {
 	.name = "memory_pressure",
-	.read = cpuset_common_file_read,
-	.write = cpuset_common_file_write,
+	.read_uint = cpuset_read_uint,
+	.write_uint = cpuset_write_uint,
 	.private = FILE_MEMORY_PRESSURE,
 };
 
 static struct cftype cft_spread_page = {
 	.name = "memory_spread_page",
-	.read = cpuset_common_file_read,
-	.write = cpuset_common_file_write,
+	.read_uint = cpuset_read_uint,
+	.write_uint = cpuset_write_uint,
 	.private = FILE_SPREAD_PAGE,
 };
 
 static struct cftype cft_spread_slab = {
 	.name = "memory_spread_slab",
-	.read = cpuset_common_file_read,
-	.write = cpuset_common_file_write,
+	.read_uint = cpuset_read_uint,
+	.write_uint = cpuset_write_uint,
 	.private = FILE_SPREAD_SLAB,
 };
 
@@ -1584,7 +1592,7 @@ static void cpuset_destroy(struct cgroup
 	cpuset_update_task_memory_state();
 
 	if (is_sched_load_balance(cs))
-		update_flag(CS_SCHED_LOAD_BALANCE, cs, "0");
+		update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
 
 	number_of_cpusets--;
 	kfree(cs);

--