Merge tag 'powerpc-5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc...

[sfrench/cifs-2.6.git] / arch / powerpc / platforms / pseries / dtl.c

diff --git a/arch/powerpc/platforms/pseries/dtl.c b/arch/powerpc/platforms/pseries/dtl.c
index ab5de985a7876b2b0aef6ec922d8cb89bc8ef0c6..2b87480f2837ae3241cd2acacd50f31ce5461bcb 100644 (file)
--- a/arch/powerpc/platforms/pseries/dtl.c
+++ b/arch/powerpc/platforms/pseries/dtl.c
@@ -27,13 +27,7 @@ struct dtl {
 };
 static DEFINE_PER_CPU(struct dtl, cpu_dtl);
 
-/*
- * Dispatch trace log event mask:
- * 0x7: 0x1: voluntary virtual processor waits
- *      0x2: time-slice preempts
- *      0x4: virtual partition memory page faults
- */
-static u8 dtl_event_mask = 0x7;
+static u8 dtl_event_mask = DTL_LOG_ALL;
 
 
 /*
@@ -48,7 +42,6 @@ struct dtl_ring {
        struct dtl_entry *write_ptr;
        struct dtl_entry *buf;
        struct dtl_entry *buf_end;
-       u8      saved_dtl_mask;
 };
 
 static DEFINE_PER_CPU(struct dtl_ring, dtl_rings);
@@ -98,7 +91,6 @@ static int dtl_start(struct dtl *dtl)
        dtlr->write_ptr = dtl->buf;
 
        /* enable event logging */
-       dtlr->saved_dtl_mask = lppaca_of(dtl->cpu).dtl_enable_mask;
        lppaca_of(dtl->cpu).dtl_enable_mask |= dtl_event_mask;
 
        dtl_consumer = consume_dtle;
@@ -116,7 +108,7 @@ static void dtl_stop(struct dtl *dtl)
        dtlr->buf = NULL;
 
        /* restore dtl_enable_mask */
-       lppaca_of(dtl->cpu).dtl_enable_mask = dtlr->saved_dtl_mask;
+       lppaca_of(dtl->cpu).dtl_enable_mask = DTL_LOG_PREEMPT;
 
        if (atomic_dec_and_test(&dtl_count))
                dtl_consumer = NULL;
@@ -188,11 +180,16 @@ static int dtl_enable(struct dtl *dtl)
        if (dtl->buf)
                return -EBUSY;
 
+       /* ensure there are no other conflicting dtl users */
+       if (!read_trylock(&dtl_access_lock))
+               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);
+               read_unlock(&dtl_access_lock);
                return -ENOMEM;
        }
 
@@ -209,8 +206,11 @@ static int dtl_enable(struct dtl *dtl)
        }
        spin_unlock(&dtl->lock);
 
-       if (rc)
+       if (rc) {
+               read_unlock(&dtl_access_lock);
                kmem_cache_free(dtl_cache, buf);
+       }
+
        return rc;
 }
 
@@ -222,6 +222,7 @@ static void dtl_disable(struct dtl *dtl)
        dtl->buf = NULL;
        dtl->buf_entries = 0;
        spin_unlock(&dtl->lock);
+       read_unlock(&dtl_access_lock);
 }
 
 /* file interface */