@@ -88,6 +88,8 @@ static inline long register_dtl(unsigned long cpu, unsigned long vpa)
return vpa_call(H_VPA_REG_DTL, cpu, vpa);
}
+extern bool register_dtl_buffer_access(bool global);
+extern void unregister_dtl_buffer_access(bool global);
extern void register_dtl_buffer(int cpu);
extern void alloc_dtl_buffers(void);
extern void vpa_init(int cpu);
@@ -193,11 +193,15 @@ static int dtl_enable(struct dtl *dtl)
if (dtl->buf)
return -EBUSY;
+ if (register_dtl_buffer_access(false))
+ return -EBUSY;
+
n_entries = dtl_buf_entries;
buf = kmem_cache_alloc_node(dtl_cache, GFP_KERNEL, cpu_to_node(dtl->cpu));
if (!buf) {
printk(KERN_WARNING "%s: buffer alloc failed for cpu %d\n",
__func__, dtl->cpu);
+ unregister_dtl_buffer_access(false);
return -ENOMEM;
}
@@ -214,8 +218,11 @@ static int dtl_enable(struct dtl *dtl)
}
spin_unlock(&dtl->lock);
- if (rc)
+ if (rc) {
+ unregister_dtl_buffer_access(false);
kmem_cache_free(dtl_cache, buf);
+ }
+
return rc;
}
@@ -227,6 +234,7 @@ static void dtl_disable(struct dtl *dtl)
dtl->buf = NULL;
dtl->buf_entries = 0;
spin_unlock(&dtl->lock);
+ unregister_dtl_buffer_access(false);
}
/* file interface */
@@ -65,6 +65,42 @@ EXPORT_SYMBOL(plpar_hcall);
EXPORT_SYMBOL(plpar_hcall9);
EXPORT_SYMBOL(plpar_hcall_norets);
+static DEFINE_SPINLOCK(dtl_buffer_refctr_lock);
+static unsigned int dtl_buffer_global_refctr, dtl_buffer_percpu_refctr;
+
+bool register_dtl_buffer_access(bool global)
+{
+ int rc = 0;
+
+ spin_lock(&dtl_buffer_refctr_lock);
+
+ if ((global && (dtl_buffer_global_refctr || dtl_buffer_percpu_refctr))
+ || (!global && dtl_buffer_global_refctr)) {
+ rc = -1;
+ } else {
+ if (global)
+ dtl_buffer_global_refctr++;
+ else
+ dtl_buffer_percpu_refctr++;
+ }
+
+ spin_unlock(&dtl_buffer_refctr_lock);
+
+ return rc;
+}
+
+void unregister_dtl_buffer_access(bool global)
+{
+ spin_lock(&dtl_buffer_refctr_lock);
+
+ if (global)
+ dtl_buffer_global_refctr--;
+ else
+ dtl_buffer_percpu_refctr--;
+
+ spin_unlock(&dtl_buffer_refctr_lock);
+}
+
void alloc_dtl_buffers(void)
{
int cpu;
Since we would be introducing a new user of the DTL buffer in a subsequent patch, add helpers to gatekeep use of the DTL buffer. The current usage of the DTL buffer from debugfs is at a per-cpu level (corresponding to the cpu debugfs file that is opened). Subsequently, we will have users enabling/accessing DTLB for all online cpus. These helpers allow any number of per-cpu users, or a single global user exclusively. Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> --- arch/powerpc/include/asm/plpar_wrappers.h | 2 ++ arch/powerpc/platforms/pseries/dtl.c | 10 ++++++- arch/powerpc/platforms/pseries/lpar.c | 36 +++++++++++++++++++++++ 3 files changed, 47 insertions(+), 1 deletion(-)