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Diffstat (limited to 'kernel/smp.c')
-rw-r--r--kernel/smp.c119
1 files changed, 73 insertions, 46 deletions
diff --git a/kernel/smp.c b/kernel/smp.c
index 9f1181375141..856562b80794 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -23,10 +23,8 @@
#include "smpboot.h"
-enum {
- CSD_FLAG_LOCK = 0x01,
- CSD_FLAG_SYNCHRONOUS = 0x02,
-};
+
+#define CSD_TYPE(_csd) ((_csd)->flags & CSD_FLAG_TYPE_MASK)
struct call_function_data {
call_single_data_t __percpu *csd;
@@ -137,15 +135,33 @@ static DEFINE_PER_CPU_SHARED_ALIGNED(call_single_data_t, csd_data);
extern void send_call_function_single_ipi(int cpu);
+void __smp_call_single_queue(int cpu, struct llist_node *node)
+{
+ /*
+ * The list addition should be visible before sending the IPI
+ * handler locks the list to pull the entry off it because of
+ * normal cache coherency rules implied by spinlocks.
+ *
+ * If IPIs can go out of order to the cache coherency protocol
+ * in an architecture, sufficient synchronisation should be added
+ * to arch code to make it appear to obey cache coherency WRT
+ * locking and barrier primitives. Generic code isn't really
+ * equipped to do the right thing...
+ */
+ if (llist_add(node, &per_cpu(call_single_queue, cpu)))
+ send_call_function_single_ipi(cpu);
+}
+
/*
* Insert a previously allocated call_single_data_t element
* for execution on the given CPU. data must already have
* ->func, ->info, and ->flags set.
*/
-static int generic_exec_single(int cpu, call_single_data_t *csd,
- smp_call_func_t func, void *info)
+static int generic_exec_single(int cpu, call_single_data_t *csd)
{
if (cpu == smp_processor_id()) {
+ smp_call_func_t func = csd->func;
+ void *info = csd->info;
unsigned long flags;
/*
@@ -159,28 +175,12 @@ static int generic_exec_single(int cpu, call_single_data_t *csd,
return 0;
}
-
if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) {
csd_unlock(csd);
return -ENXIO;
}
- csd->func = func;
- csd->info = info;
-
- /*
- * The list addition should be visible before sending the IPI
- * handler locks the list to pull the entry off it because of
- * normal cache coherency rules implied by spinlocks.
- *
- * If IPIs can go out of order to the cache coherency protocol
- * in an architecture, sufficient synchronisation should be added
- * to arch code to make it appear to obey cache coherency WRT
- * locking and barrier primitives. Generic code isn't really
- * equipped to do the right thing...
- */
- if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)))
- send_call_function_single_ipi(cpu);
+ __smp_call_single_queue(cpu, &csd->llist);
return 0;
}
@@ -194,16 +194,10 @@ static int generic_exec_single(int cpu, call_single_data_t *csd,
void generic_smp_call_function_single_interrupt(void)
{
flush_smp_call_function_queue(true);
-
- /*
- * Handle irq works queued remotely by irq_work_queue_on().
- * Smp functions above are typically synchronous so they
- * better run first since some other CPUs may be busy waiting
- * for them.
- */
- irq_work_run();
}
+extern void irq_work_single(void *);
+
/**
* flush_smp_call_function_queue - Flush pending smp-call-function callbacks
*
@@ -241,9 +235,21 @@ static void flush_smp_call_function_queue(bool warn_cpu_offline)
* We don't have to use the _safe() variant here
* because we are not invoking the IPI handlers yet.
*/
- llist_for_each_entry(csd, entry, llist)
- pr_warn("IPI callback %pS sent to offline CPU\n",
- csd->func);
+ llist_for_each_entry(csd, entry, llist) {
+ switch (CSD_TYPE(csd)) {
+ case CSD_TYPE_ASYNC:
+ case CSD_TYPE_SYNC:
+ case CSD_TYPE_IRQ_WORK:
+ pr_warn("IPI callback %pS sent to offline CPU\n",
+ csd->func);
+ break;
+
+ default:
+ pr_warn("IPI callback, unknown type %d, sent to offline CPU\n",
+ CSD_TYPE(csd));
+ break;
+ }
+ }
}
/*
@@ -251,16 +257,17 @@ static void flush_smp_call_function_queue(bool warn_cpu_offline)
*/
prev = NULL;
llist_for_each_entry_safe(csd, csd_next, entry, llist) {
- smp_call_func_t func = csd->func;
- void *info = csd->info;
-
/* Do we wait until *after* callback? */
- if (csd->flags & CSD_FLAG_SYNCHRONOUS) {
+ if (CSD_TYPE(csd) == CSD_TYPE_SYNC) {
+ smp_call_func_t func = csd->func;
+ void *info = csd->info;
+
if (prev) {
prev->next = &csd_next->llist;
} else {
entry = &csd_next->llist;
}
+
func(info);
csd_unlock(csd);
} else {
@@ -272,11 +279,17 @@ static void flush_smp_call_function_queue(bool warn_cpu_offline)
* Second; run all !SYNC callbacks.
*/
llist_for_each_entry_safe(csd, csd_next, entry, llist) {
- smp_call_func_t func = csd->func;
- void *info = csd->info;
+ int type = CSD_TYPE(csd);
- csd_unlock(csd);
- func(info);
+ if (type == CSD_TYPE_ASYNC) {
+ smp_call_func_t func = csd->func;
+ void *info = csd->info;
+
+ csd_unlock(csd);
+ func(info);
+ } else if (type == CSD_TYPE_IRQ_WORK) {
+ irq_work_single(csd);
+ }
}
}
@@ -305,7 +318,7 @@ int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
{
call_single_data_t *csd;
call_single_data_t csd_stack = {
- .flags = CSD_FLAG_LOCK | CSD_FLAG_SYNCHRONOUS,
+ .flags = CSD_FLAG_LOCK | CSD_TYPE_SYNC,
};
int this_cpu;
int err;
@@ -339,7 +352,10 @@ int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
csd_lock(csd);
}
- err = generic_exec_single(cpu, csd, func, info);
+ csd->func = func;
+ csd->info = info;
+
+ err = generic_exec_single(cpu, csd);
if (wait)
csd_lock_wait(csd);
@@ -385,7 +401,7 @@ int smp_call_function_single_async(int cpu, call_single_data_t *csd)
csd->flags = CSD_FLAG_LOCK;
smp_wmb();
- err = generic_exec_single(cpu, csd, csd->func, csd->info);
+ err = generic_exec_single(cpu, csd);
out:
preempt_enable();
@@ -500,7 +516,7 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
csd_lock(csd);
if (wait)
- csd->flags |= CSD_FLAG_SYNCHRONOUS;
+ csd->flags |= CSD_TYPE_SYNC;
csd->func = func;
csd->info = info;
if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu)))
@@ -632,6 +648,17 @@ void __init smp_init(void)
{
int num_nodes, num_cpus;
+ /*
+ * Ensure struct irq_work layout matches so that
+ * flush_smp_call_function_queue() can do horrible things.
+ */
+ BUILD_BUG_ON(offsetof(struct irq_work, llnode) !=
+ offsetof(struct __call_single_data, llist));
+ BUILD_BUG_ON(offsetof(struct irq_work, func) !=
+ offsetof(struct __call_single_data, func));
+ BUILD_BUG_ON(offsetof(struct irq_work, flags) !=
+ offsetof(struct __call_single_data, flags));
+
idle_threads_init();
cpuhp_threads_init();
generated by cgit v1.2.3-58-ga151 (git 2.39.0) at 2024-12-25 02:01:24 +0000