-#ifndef _LINUX_RING_BUFFER_BACKEND_H
-#define _LINUX_RING_BUFFER_BACKEND_H
-
/*
- * linux/ringbuffer/backend.h
+ * SPDX-License-Identifier: LGPL-2.1-only
*
- * Copyright (C) 2008-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
*
* Ring buffer backend (API).
*
- * Dual LGPL v2.1/GPL v2 license.
- *
* Credits to Steven Rostedt for proposing to use an extra-subbuffer owned by
* the reader in flight recorder mode.
*/
-#include <unistd.h>
+#ifndef _LTTNG_RING_BUFFER_BACKEND_H
+#define _LTTNG_RING_BUFFER_BACKEND_H
-#include "ust/core.h"
+#include <stddef.h>
+#include <unistd.h>
/* Internal helpers */
#include "backend_internal.h"
/* Ring buffer backend access (read/write) */
-extern size_t lib_ring_buffer_read(struct lib_ring_buffer_backend *bufb,
+extern size_t lib_ring_buffer_read(struct lttng_ust_lib_ring_buffer_backend *bufb,
size_t offset, void *dest, size_t len,
struct lttng_ust_shm_handle *handle);
-extern int lib_ring_buffer_read_cstr(struct lib_ring_buffer_backend *bufb,
+extern int lib_ring_buffer_read_cstr(struct lttng_ust_lib_ring_buffer_backend *bufb,
size_t offset, void *dest, size_t len,
struct lttng_ust_shm_handle *handle);
* as long as the write is never bigger than a page size.
*/
extern void *
-lib_ring_buffer_offset_address(struct lib_ring_buffer_backend *bufb,
+lib_ring_buffer_offset_address(struct lttng_ust_lib_ring_buffer_backend *bufb,
size_t offset,
struct lttng_ust_shm_handle *handle);
extern void *
-lib_ring_buffer_read_offset_address(struct lib_ring_buffer_backend *bufb,
+lib_ring_buffer_read_offset_address(struct lttng_ust_lib_ring_buffer_backend *bufb,
size_t offset,
struct lttng_ust_shm_handle *handle);
* backend-specific memcpy() operation. Calls the slow path (_ring_buffer_write)
* if copy is crossing a page boundary.
*/
-static inline
-void lib_ring_buffer_write(const struct lib_ring_buffer_config *config,
- struct lib_ring_buffer_ctx *ctx,
+static inline __attribute__((always_inline))
+void lib_ring_buffer_write(const struct lttng_ust_lib_ring_buffer_config *config,
+ struct lttng_ust_lib_ring_buffer_ctx *ctx,
const void *src, size_t len)
{
- struct lib_ring_buffer_backend *bufb = &ctx->buf->backend;
struct channel_backend *chanb = &ctx->chan->backend;
struct lttng_ust_shm_handle *handle = ctx->handle;
- size_t sbidx;
size_t offset = ctx->buf_offset;
- struct lib_ring_buffer_backend_pages_shmp *rpages;
- unsigned long sb_bindex, id;
-
- offset &= chanb->buf_size - 1;
- sbidx = offset >> chanb->subbuf_size_order;
- id = shmp_index(handle, bufb->buf_wsb, sbidx)->id;
- sb_bindex = subbuffer_id_get_index(config, id);
- rpages = shmp_index(handle, bufb->array, sb_bindex);
- CHAN_WARN_ON(ctx->chan,
- config->mode == RING_BUFFER_OVERWRITE
- && subbuffer_id_is_noref(config, id));
+ struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
+ void *p;
+
+ if (caa_unlikely(!len))
+ return;
+ /*
+ * Underlying layer should never ask for writes across
+ * subbuffers.
+ */
+ CHAN_WARN_ON(chanb, (offset & (chanb->buf_size - 1)) + len > chanb->buf_size);
+ backend_pages = lib_ring_buffer_get_backend_pages_from_ctx(config, ctx);
+ if (caa_unlikely(!backend_pages)) {
+ if (lib_ring_buffer_backend_get_pages(config, ctx, &backend_pages))
+ return;
+ }
+ p = shmp_index(handle, backend_pages->p, offset & (chanb->subbuf_size - 1));
+ if (caa_unlikely(!p))
+ return;
+ lib_ring_buffer_do_copy(config, p, src, len);
+ ctx->buf_offset += len;
+}
+
+/*
+ * Copy up to @len string bytes from @src to @dest. Stop whenever a NULL
+ * terminating character is found in @src. Returns the number of bytes
+ * copied. Does *not* terminate @dest with NULL terminating character.
+ */
+static inline __attribute__((always_inline))
+size_t lib_ring_buffer_do_strcpy(const struct lttng_ust_lib_ring_buffer_config *config,
+ char *dest, const char *src, size_t len)
+{
+ size_t count;
+
+ for (count = 0; count < len; count++) {
+ char c;
+
+ /*
+ * Only read source character once, in case it is
+ * modified concurrently.
+ */
+ c = CMM_LOAD_SHARED(src[count]);
+ if (!c)
+ break;
+ lib_ring_buffer_do_copy(config, &dest[count], &c, 1);
+ }
+ return count;
+}
+
+/**
+ * lib_ring_buffer_strcpy - write string data to a buffer backend
+ * @config : ring buffer instance configuration
+ * @ctx: ring buffer context. (input arguments only)
+ * @src : source pointer to copy from
+ * @len : length of data to copy
+ * @pad : character to use for padding
+ *
+ * This function copies @len - 1 bytes of string data from a source
+ * pointer to a buffer backend, followed by a terminating '\0'
+ * character, at the current context offset. This is more or less a
+ * buffer backend-specific strncpy() operation. If a terminating '\0'
+ * character is found in @src before @len - 1 characters are copied, pad
+ * the buffer with @pad characters (e.g. '#').
+ */
+static inline __attribute__((always_inline))
+void lib_ring_buffer_strcpy(const struct lttng_ust_lib_ring_buffer_config *config,
+ struct lttng_ust_lib_ring_buffer_ctx *ctx,
+ const char *src, size_t len, int pad)
+{
+ struct channel_backend *chanb = &ctx->chan->backend;
+ struct lttng_ust_shm_handle *handle = ctx->handle;
+ size_t count;
+ size_t offset = ctx->buf_offset;
+ struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
+ void *p;
+
+ if (caa_unlikely(!len))
+ return;
/*
* Underlying layer should never ask for writes across
* subbuffers.
*/
- CHAN_WARN_ON(chanb, offset >= chanb->buf_size);
- lib_ring_buffer_do_copy(config,
- shmp_index(handle, shmp(handle, rpages->shmp)->p, offset & (chanb->subbuf_size - 1)),
- src, len);
+ CHAN_WARN_ON(chanb, (offset & (chanb->buf_size - 1)) + len > chanb->buf_size);
+ backend_pages = lib_ring_buffer_get_backend_pages_from_ctx(config, ctx);
+ if (caa_unlikely(!backend_pages)) {
+ if (lib_ring_buffer_backend_get_pages(config, ctx, &backend_pages))
+ return;
+ }
+ p = shmp_index(handle, backend_pages->p, offset & (chanb->subbuf_size - 1));
+ if (caa_unlikely(!p))
+ return;
+
+ count = lib_ring_buffer_do_strcpy(config, p, src, len - 1);
+ offset += count;
+ /* Padding */
+ if (caa_unlikely(count < len - 1)) {
+ size_t pad_len = len - 1 - count;
+
+ p = shmp_index(handle, backend_pages->p, offset & (chanb->subbuf_size - 1));
+ if (caa_unlikely(!p))
+ return;
+ lib_ring_buffer_do_memset(p, pad, pad_len);
+ offset += pad_len;
+ }
+ /* Final '\0' */
+ p = shmp_index(handle, backend_pages->p, offset & (chanb->subbuf_size - 1));
+ if (caa_unlikely(!p))
+ return;
+ lib_ring_buffer_do_memset(p, '\0', 1);
ctx->buf_offset += len;
}
*/
static inline
unsigned long lib_ring_buffer_get_records_unread(
- const struct lib_ring_buffer_config *config,
- struct lib_ring_buffer *buf,
+ const struct lttng_ust_lib_ring_buffer_config *config,
+ struct lttng_ust_lib_ring_buffer *buf,
struct lttng_ust_shm_handle *handle)
{
- struct lib_ring_buffer_backend *bufb = &buf->backend;
- struct lib_ring_buffer_backend_pages_shmp *pages;
- unsigned long records_unread = 0, sb_bindex, id;
+ struct lttng_ust_lib_ring_buffer_backend *bufb = &buf->backend;
+ unsigned long records_unread = 0, sb_bindex;
unsigned int i;
+ struct channel *chan;
- for (i = 0; i < shmp(handle, bufb->chan)->backend.num_subbuf; i++) {
- id = shmp_index(handle, bufb->buf_wsb, i)->id;
- sb_bindex = subbuffer_id_get_index(config, id);
- pages = shmp_index(handle, bufb->array, sb_bindex);
- records_unread += v_read(config, &shmp(handle, pages->shmp)->records_unread);
+ chan = shmp(handle, bufb->chan);
+ if (!chan)
+ return 0;
+ for (i = 0; i < chan->backend.num_subbuf; i++) {
+ struct lttng_ust_lib_ring_buffer_backend_subbuffer *wsb;
+ struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages;
+ struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
+
+ wsb = shmp_index(handle, bufb->buf_wsb, i);
+ if (!wsb)
+ return 0;
+ sb_bindex = subbuffer_id_get_index(config, wsb->id);
+ rpages = shmp_index(handle, bufb->array, sb_bindex);
+ if (!rpages)
+ return 0;
+ backend_pages = shmp(handle, rpages->shmp);
+ if (!backend_pages)
+ return 0;
+ records_unread += v_read(config, &backend_pages->records_unread);
}
if (config->mode == RING_BUFFER_OVERWRITE) {
- id = bufb->buf_rsb.id;
- sb_bindex = subbuffer_id_get_index(config, id);
- pages = shmp_index(handle, bufb->array, sb_bindex);
- records_unread += v_read(config, &shmp(handle, pages->shmp)->records_unread);
+ struct lttng_ust_lib_ring_buffer_backend_pages_shmp *rpages;
+ struct lttng_ust_lib_ring_buffer_backend_pages *backend_pages;
+
+ sb_bindex = subbuffer_id_get_index(config, bufb->buf_rsb.id);
+ rpages = shmp_index(handle, bufb->array, sb_bindex);
+ if (!rpages)
+ return 0;
+ backend_pages = shmp(handle, rpages->shmp);
+ if (!backend_pages)
+ return 0;
+ records_unread += v_read(config, &backend_pages->records_unread);
}
return records_unread;
}
-#endif /* _LINUX_RING_BUFFER_BACKEND_H */
+#endif /* _LTTNG_RING_BUFFER_BACKEND_H */
projects / lttng-ust.git / blobdiff