[PATCH v1 28/31] x86/resctrl: Drop __init/__exit on assorted symbols

James Morse
2024-03-21T16:53:00Z

Because ARM's MPAM controls are probed using MMIO, resctrl can't be
initialised until enough CPUs are online to have determined the
system-wide supported num_closid. Arm64 also supports 'late onlined
secondaries', where only a subset of CPUs are online during boot.

These two combine to mean the MPAM driver may not be able to initialise
resctrl until user-space has brought 'enough' CPUs online.

To allow MPAM to initialise resctrl after __init text has been free'd,
remove all the __init markings from resctrl.

The existing __exit markings cause these functions to be removed by the
linker as it has never been possible to build resctrl as a module. MPAM
has an error interrupt which causes the driver to reset and disable
itself. Remove the __exit markings to allow the MPAM driver to tear down
resctrl when an error occurs.

Signed-off-by: James Morse <james.morse@arm.com>
---
If 'late onlined secondaries' is an alien concept, I can add a worked
example to the commit message:
If a system has two L3 caches, but during boot only CPU-0 is online,
then no CPU is able to probe the features of the second L3 cache.
It's not until user-space brings other CPUs online that the MPAM
driver can finally get a glimpse of all the hardware to determine
what properties the system has.
---
arch/x86/kernel/cpu/resctrl/internal.h | 2 +-
arch/x86/kernel/cpu/resctrl/monitor.c | 4 ++--
arch/x86/kernel/cpu/resctrl/rdtgroup.c | 8 ++++----
include/linux/resctrl.h | 4 ++--
4 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 3a3962736061..56218193a8ba 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -457,7 +457,7 @@ void closid_free(int closid);
int alloc_rmid(u32 closid);
void free_rmid(u32 closid, u32 rmid);
int rdt_get_mon_l3_config(struct rdt_resource *r);
-void __exit resctrl_mon_resource_exit(void);
+void resctrl_mon_resource_exit(void);
bool rdt_cpu_has(int flag);
void mon_event_count(void *info);
int rdtgroup_mondata_show(struct seq_file *m, void *arg);
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index 8b316d9acc3b..7e6fca138cb7 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -954,7 +954,7 @@ static int dom_data_init(struct rdt_resource *r)
return err;
}

-static void __exit dom_data_exit(struct rdt_resource *r)
+static void dom_data_exit(struct rdt_resource *r)
{
if (!r->mon_capable)
return;
@@ -1076,7 +1076,7 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
return 0;
}

-void __exit resctrl_mon_resource_exit(void)
+void resctrl_mon_resource_exit(void)
{
struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_L3);

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 218aebd6387f..1425a33d201d 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -2069,7 +2069,7 @@ static struct rftype *rdtgroup_get_rftype_by_name(const char *name)
return NULL;
}

-static void __init thread_throttle_mode_init(void)
+static void thread_throttle_mode_init(void)
{
struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_MBA);
struct rftype *rft;
@@ -3997,7 +3997,7 @@ static void rdtgroup_destroy_root(void)
rdtgroup_default.kn = NULL;
}

-static void __init rdtgroup_setup_default(void)
+static void rdtgroup_setup_default(void)
{
mutex_lock(&rdtgroup_mutex);

@@ -4190,7 +4190,7 @@ void resctrl_offline_cpu(unsigned int cpu)
*
* Return: 0 on success or -errno
*/
-int __init resctrl_init(void)
+int resctrl_init(void)
{
int ret = 0;

@@ -4244,7 +4244,7 @@ int __init resctrl_init(void)
return ret;
}

-void __exit resctrl_exit(void)
+void resctrl_exit(void)
{
debugfs_remove_recursive(debugfs_resctrl);
unregister_filesystem(&rdt_fs_type);
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index f463fb949677..5da55e58f229 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -393,7 +393,7 @@ void resctrl_arch_reset_rmid_all(struct rdt_resource *r, struct rdt_domain *d);
extern unsigned int resctrl_rmid_realloc_threshold;
extern unsigned int resctrl_rmid_realloc_limit;

-int __init resctrl_init(void);
-void __exit resctrl_exit(void);
+int resctrl_init(void);
+void resctrl_exit(void);

#endif /* _RESCTRL_H */
--
2.39.2