This patch adds the ability to explicitly specify the per-cpu buffer
to reserve space in. Needed for early DTI tracing.
Signed-off-by: Tom Zanussi <[email protected]>
Signed-off-by: David Wilder <[email protected]>
---
relay.h | 33 +++++++++++++++++++++++++++++++++
1 file changed, 33 insertions(+)
diff --git a/include/linux/relay.h b/include/linux/relay.h
index 6caedef..37a7306 100644
--- a/include/linux/relay.h
+++ b/include/linux/relay.h
@@ -269,6 +269,39 @@ static inline void *relay_reserve(struct rchan *chan, size_t length)
}
/**
+ * relay_reserve_cpu - reserve slot in given cpu's channel buffer
+ * @chan: relay channel
+ * @length: number of bytes to reserve
+ * @cpu: cpu to log to
+ *
+ * Returns pointer to reserved slot, NULL if full.
+ *
+ * Reserves a slot in the given cpu's channel buffer.
+ * Does not protect the buffer at all - caller must provide
+ * appropriate synchronization.
+ *
+ * NOTE: this is almost certainly not the function you want -
+ * use relay_reserve() instead for normal logging. This version
+ * is specialized for things like early tracing.
+ */
+static inline void *relay_reserve_cpu(struct rchan *chan, size_t length,
+ unsigned int cpu)
+{
+ void *reserved;
+ struct rchan_buf *buf = chan->buf[cpu];
+
+ if (unlikely(buf->offset + length > buf->chan->subbuf_size)) {
+ length = relay_switch_subbuf(buf, length);
+ if (!length)
+ return NULL;
+ }
+ reserved = buf->data + buf->offset;
+ buf->offset += length;
+
+ return reserved;
+}
+
+/**
* subbuf_start_reserve - reserve bytes at the start of a sub-buffer
* @buf: relay channel buffer
* @length: number of bytes to reserve