X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=lib%2Fringbuffer%2Fbackend.h;h=541dc531ca76765e990635edc1c2a526e2ccdddb;hb=4ea00e4f764eb18686121161a98e4ef442fed2c0;hp=47bc1798334188a2c31c2c89e71c12ad81e4b42e;hpb=c595c36f753dde1bccbee455bbfeb8b31b7f41d1;p=lttng-modules.git

diff --git a/lib/ringbuffer/backend.h b/lib/ringbuffer/backend.h
index 47bc1798..541dc531 100644
--- a/lib/ringbuffer/backend.h
+++ b/lib/ringbuffer/backend.h
@@ -103,6 +103,115 @@ void lib_ring_buffer_write(const struct lib_ring_buffer_config *config,
 	ctx->buf_offset += len;
 }
 
+/**
+ * lib_ring_buffer_memset - write len bytes of c to a buffer backend
+ * @config : ring buffer instance configuration
+ * @bufb : ring buffer backend
+ * @offset : offset within the buffer
+ * @c : the byte to copy
+ * @len : number of bytes to copy
+ *
+ * This function writes "len" bytes of "c" to a buffer backend, at a specific
+ * offset. This is more or less a buffer backend-specific memset() operation.
+ * Calls the slow path (_ring_buffer_memset) if write is crossing a page
+ * boundary.
+ */
+static inline
+void lib_ring_buffer_memset(const struct lib_ring_buffer_config *config,
+			    struct lib_ring_buffer_ctx *ctx, int c, size_t len)
+{
+
+	struct lib_ring_buffer_backend *bufb = &ctx->buf->backend;
+	struct channel_backend *chanb = &ctx->chan->backend;
+	size_t sbidx, index;
+	size_t offset = ctx->buf_offset;
+	ssize_t pagecpy;
+	struct lib_ring_buffer_backend_pages *rpages;
+	unsigned long sb_bindex, id;
+
+	offset &= chanb->buf_size - 1;
+	sbidx = offset >> chanb->subbuf_size_order;
+	index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT;
+	pagecpy = min_t(size_t, len, (-offset) & ~PAGE_MASK);
+	id = bufb->buf_wsb[sbidx].id;
+	sb_bindex = subbuffer_id_get_index(config, id);
+	rpages = bufb->array[sb_bindex];
+	CHAN_WARN_ON(ctx->chan,
+		     config->mode == RING_BUFFER_OVERWRITE
+		     && subbuffer_id_is_noref(config, id));
+	if (likely(pagecpy == len))
+		lib_ring_buffer_do_memset(rpages->p[index].virt
+					  + (offset & ~PAGE_MASK),
+					  c, len);
+	else
+		_lib_ring_buffer_memset(bufb, offset, c, len, 0);
+	ctx->buf_offset += len;
+}
+
+/**
+ * lib_ring_buffer_copy_from_user - write userspace data to a buffer backend
+ * @config : ring buffer instance configuration
+ * @ctx: ring buffer context. (input arguments only)
+ * @src : userspace source pointer to copy from
+ * @len : length of data to copy
+ *
+ * This function copies "len" bytes of data from a userspace pointer to a
+ * buffer backend, at the current context offset. This is more or less a buffer
+ * backend-specific memcpy() operation. Calls the slow path
+ * (_ring_buffer_write_from_user) if copy is crossing a page boundary.
+ */
+static inline
+void lib_ring_buffer_copy_from_user(const struct lib_ring_buffer_config *config,
+				    struct lib_ring_buffer_ctx *ctx,
+				    const void __user *src, size_t len)
+{
+	struct lib_ring_buffer_backend *bufb = &ctx->buf->backend;
+	struct channel_backend *chanb = &ctx->chan->backend;
+	size_t sbidx, index;
+	size_t offset = ctx->buf_offset;
+	ssize_t pagecpy;
+	struct lib_ring_buffer_backend_pages *rpages;
+	unsigned long sb_bindex, id;
+	unsigned long ret;
+
+	offset &= chanb->buf_size - 1;
+	sbidx = offset >> chanb->subbuf_size_order;
+	index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT;
+	pagecpy = min_t(size_t, len, (-offset) & ~PAGE_MASK);
+	id = bufb->buf_wsb[sbidx].id;
+	sb_bindex = subbuffer_id_get_index(config, id);
+	rpages = bufb->array[sb_bindex];
+	CHAN_WARN_ON(ctx->chan,
+		     config->mode == RING_BUFFER_OVERWRITE
+		     && subbuffer_id_is_noref(config, id));
+
+	if (unlikely(!access_ok(VERIFY_READ, src, len)))
+		goto fill_buffer;
+
+	if (likely(pagecpy == len)) {
+		ret = lib_ring_buffer_do_copy_from_user(
+			rpages->p[index].virt + (offset & ~PAGE_MASK),
+			src, len);
+		if (unlikely(ret > 0)) {
+			len -= (pagecpy - ret);
+			offset += (pagecpy - ret);
+			goto fill_buffer;
+		}
+	} else {
+		_lib_ring_buffer_copy_from_user(bufb, offset, src, len, 0);
+	}
+	ctx->buf_offset += len;
+
+	return;
+
+fill_buffer:
+	/*
+	 * In the error path we call the slow path version to avoid
+	 * the pollution of static inline code.
+	 */
+	_lib_ring_buffer_memset(bufb, offset, 0, len, 0);
+}
+
 /*
  * This accessor counts the number of unread records in a buffer.
  * It only provides a consistent value if no reads not writes are performed