Cleanup: lib ring buffer: rename pagecpy local variable

Rename pagecpy local variable to bytes_left_in_page, which has a clearer
semantic. Also remove the unused pagecpy parameter from slow paths which
was always 0.

Also add a missing __user annotation on @src of
the _lib_ring_buffer_copy_from_user_inatomic prototype.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I22a85cb8e94a65aaa80ca49951479243477ac600

diff --git a/include/ringbuffer/backend.h b/include/ringbuffer/backend.h
index 13f67a4ea8c51e48f8832ff1813931a772997442..c6e613c1d991101b80b332f5500eb58984080449 100644 (file)
--- a/include/ringbuffer/backend.h
+++ b/include/ringbuffer/backend.h
@@ -77,7 +77,7 @@ void lib_ring_buffer_write(const struct lttng_kernel_ring_buffer_config *config,
 {
        struct lttng_kernel_ring_buffer_backend *bufb = &ctx->priv.buf->backend;
        struct channel_backend *chanb = &ctx->priv.chan->backend;
-       size_t index, pagecpy;
+       size_t index, bytes_left_in_page;
        size_t offset = ctx->priv.buf_offset;
        struct lttng_kernel_ring_buffer_backend_pages *backend_pages;
 
@@ -87,14 +87,14 @@ void lib_ring_buffer_write(const struct lttng_kernel_ring_buffer_config *config,
                lib_ring_buffer_get_backend_pages_from_ctx(config, ctx);
        offset &= chanb->buf_size - 1;
        index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT;
-       pagecpy = min_t(size_t, len, (-offset) & ~PAGE_MASK);
-       if (likely(pagecpy == len))
+       bytes_left_in_page = min_t(size_t, len, (-offset) & ~PAGE_MASK);
+       if (likely(bytes_left_in_page == len))
                lib_ring_buffer_do_copy(config,
                                        backend_pages->p[index].virt
                                            + (offset & ~PAGE_MASK),
                                        src, len);
        else
-               _lib_ring_buffer_write(bufb, offset, src, len, 0);
+               _lib_ring_buffer_write(bufb, offset, src, len);
        ctx->priv.buf_offset += len;
 }
 
@@ -118,7 +118,7 @@ void lib_ring_buffer_memset(const struct lttng_kernel_ring_buffer_config *config
 
        struct lttng_kernel_ring_buffer_backend *bufb = &ctx->priv.buf->backend;
        struct channel_backend *chanb = &ctx->priv.chan->backend;
-       size_t index, pagecpy;
+       size_t index, bytes_left_in_page;
        size_t offset = ctx->priv.buf_offset;
        struct lttng_kernel_ring_buffer_backend_pages *backend_pages;
 
@@ -128,13 +128,13 @@ void lib_ring_buffer_memset(const struct lttng_kernel_ring_buffer_config *config
                lib_ring_buffer_get_backend_pages_from_ctx(config, ctx);
        offset &= chanb->buf_size - 1;
        index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT;
-       pagecpy = min_t(size_t, len, (-offset) & ~PAGE_MASK);
-       if (likely(pagecpy == len))
+       bytes_left_in_page = min_t(size_t, len, (-offset) & ~PAGE_MASK);
+       if (likely(bytes_left_in_page == len))
                lib_ring_buffer_do_memset(backend_pages->p[index].virt
                                          + (offset & ~PAGE_MASK),
                                          c, len);
        else
-               _lib_ring_buffer_memset(bufb, offset, c, len, 0);
+               _lib_ring_buffer_memset(bufb, offset, c, len);
        ctx->priv.buf_offset += len;
 }
 
@@ -335,7 +335,7 @@ void lib_ring_buffer_copy_from_user_inatomic(const struct lttng_kernel_ring_buff
 {
        struct lttng_kernel_ring_buffer_backend *bufb = &ctx->priv.buf->backend;
        struct channel_backend *chanb = &ctx->priv.chan->backend;
-       size_t index, pagecpy;
+       size_t index, bytes_left_in_page;
        size_t offset = ctx->priv.buf_offset;
        struct lttng_kernel_ring_buffer_backend_pages *backend_pages;
        unsigned long ret;
@@ -346,13 +346,13 @@ void lib_ring_buffer_copy_from_user_inatomic(const struct lttng_kernel_ring_buff
                lib_ring_buffer_get_backend_pages_from_ctx(config, ctx);
        offset &= chanb->buf_size - 1;
        index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT;
-       pagecpy = min_t(size_t, len, (-offset) & ~PAGE_MASK);
+       bytes_left_in_page = min_t(size_t, len, (-offset) & ~PAGE_MASK);
 
        if (unlikely(!lttng_access_ok(VERIFY_READ, src, len)))
                goto fill_buffer;
 
        pagefault_disable();
-       if (likely(pagecpy == len)) {
+       if (likely(bytes_left_in_page == len)) {
                ret = lib_ring_buffer_do_copy_from_user_inatomic(
                        backend_pages->p[index].virt + (offset & ~PAGE_MASK),
                        src, len);
@@ -361,7 +361,7 @@ void lib_ring_buffer_copy_from_user_inatomic(const struct lttng_kernel_ring_buff
                        goto fill_buffer_enable_pf;
                }
        } else {
-               _lib_ring_buffer_copy_from_user_inatomic(bufb, offset, src, len, 0);
+               _lib_ring_buffer_copy_from_user_inatomic(bufb, offset, src, len);
        }
        pagefault_enable();
        ctx->priv.buf_offset += len;
@@ -375,7 +375,7 @@ 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);
+       _lib_ring_buffer_memset(bufb, offset, 0, len);
        ctx->priv.buf_offset += len;
 }
 
@@ -455,9 +455,9 @@ 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, pad, len - 1, 0);
+       _lib_ring_buffer_memset(bufb, offset, pad, len - 1);
        offset += len - 1;
-       _lib_ring_buffer_memset(bufb, offset, '\0', 1, 0);
+       _lib_ring_buffer_memset(bufb, offset, '\0', 1);
        ctx->priv.buf_offset += len;
 }
 
@@ -535,7 +535,7 @@ 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, pad, len, 0);
+       _lib_ring_buffer_memset(bufb, offset, pad, len);
        ctx->priv.buf_offset += len;
 }
 

diff --git a/include/ringbuffer/backend_internal.h b/include/ringbuffer/backend_internal.h
index fb60f2abc3e9050d27371e3b730efb36011b644c..c8ec88cc2fd0cbdf2977cd2c3210f392a320e219 100644 (file)
--- a/include/ringbuffer/backend_internal.h
+++ b/include/ringbuffer/backend_internal.h
@@ -40,18 +40,15 @@ int lib_ring_buffer_backend_init(void);
 void lib_ring_buffer_backend_exit(void);
 
 extern void _lib_ring_buffer_write(struct lttng_kernel_ring_buffer_backend *bufb,
-                                  size_t offset, const void *src, size_t len,
-                                  size_t pagecpy);
+                                  size_t offset, const void *src, size_t len);
 extern void _lib_ring_buffer_memset(struct lttng_kernel_ring_buffer_backend *bufb,
-                                   size_t offset, int c, size_t len,
-                                   size_t pagecpy);
+                                   size_t offset, int c, size_t len);
 extern void _lib_ring_buffer_strcpy(struct lttng_kernel_ring_buffer_backend *bufb,
                                   size_t offset, const char *src, size_t len, int pad);
 extern void _lib_ring_buffer_pstrcpy(struct lttng_kernel_ring_buffer_backend *bufb,
                                   size_t offset, const char *src, size_t len, int pad);
 extern void _lib_ring_buffer_copy_from_user_inatomic(struct lttng_kernel_ring_buffer_backend *bufb,
-                                           size_t offset, const void *src,
-                                           size_t len, size_t pagecpy);
+                                           size_t offset, const void __user *src, size_t len);
 extern void _lib_ring_buffer_strcpy_from_user_inatomic(struct lttng_kernel_ring_buffer_backend *bufb,
                size_t offset, const char __user *src, size_t len, int pad);
 extern void _lib_ring_buffer_pstrcpy_from_user_inatomic(struct lttng_kernel_ring_buffer_backend *bufb,

diff --git a/src/lib/ringbuffer/ring_buffer_backend.c b/src/lib/ringbuffer/ring_buffer_backend.c
index cbc931df04b2682a29b02f3afa8e5cd60318474b..26efb2bcd70dac30d468e21ea38ed869617c2bb2 100644 (file)
--- a/src/lib/ringbuffer/ring_buffer_backend.c
+++ b/src/lib/ringbuffer/ring_buffer_backend.c
@@ -565,21 +565,17 @@ void channel_backend_free(struct channel_backend *chanb)
  * @offset : offset within the buffer
  * @src : source address
  * @len : length to write
- * @pagecpy : page size copied so far
  */
 void _lib_ring_buffer_write(struct lttng_kernel_ring_buffer_backend *bufb, size_t offset,
-                           const void *src, size_t len, size_t pagecpy)
+                           const void *src, size_t len)
 {
        struct channel_backend *chanb = &bufb->chan->backend;
        const struct lttng_kernel_ring_buffer_config *config = &chanb->config;
-       size_t sbidx, index;
+       size_t sbidx, index, bytes_left_in_page;
        struct lttng_kernel_ring_buffer_backend_pages *rpages;
        unsigned long sb_bindex, id;
 
        do {
-               len -= pagecpy;
-               src += pagecpy;
-               offset += pagecpy;
                sbidx = offset >> chanb->subbuf_size_order;
                index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT;
 
@@ -589,7 +585,7 @@ void _lib_ring_buffer_write(struct lttng_kernel_ring_buffer_backend *bufb, size_
                 */
                CHAN_WARN_ON(chanb, offset >= chanb->buf_size);
 
-               pagecpy = min_t(size_t, len, PAGE_SIZE - (offset & ~PAGE_MASK));
+               bytes_left_in_page = min_t(size_t, len, PAGE_SIZE - (offset & ~PAGE_MASK));
                id = bufb->buf_wsb[sbidx].id;
                sb_bindex = subbuffer_id_get_index(config, id);
                rpages = bufb->array[sb_bindex];
@@ -598,33 +594,31 @@ void _lib_ring_buffer_write(struct lttng_kernel_ring_buffer_backend *bufb, size_
                lib_ring_buffer_do_copy(config,
                                        rpages->p[index].virt
                                                + (offset & ~PAGE_MASK),
-                                       src, pagecpy);
-       } while (unlikely(len != pagecpy));
+                                       src, bytes_left_in_page);
+               len -= bytes_left_in_page;
+               src += bytes_left_in_page;
+               offset += bytes_left_in_page;
+       } while (unlikely(len));
 }
 EXPORT_SYMBOL_GPL(_lib_ring_buffer_write);
 
-
 /**
  * lib_ring_buffer_memset - write len bytes of c to a ring_buffer buffer.
  * @bufb : buffer backend
  * @offset : offset within the buffer
  * @c : the byte to write
  * @len : length to write
- * @pagecpy : page size copied so far
  */
 void _lib_ring_buffer_memset(struct lttng_kernel_ring_buffer_backend *bufb,
-                            size_t offset,
-                            int c, size_t len, size_t pagecpy)
+                            size_t offset, int c, size_t len)
 {
        struct channel_backend *chanb = &bufb->chan->backend;
        const struct lttng_kernel_ring_buffer_config *config = &chanb->config;
-       size_t sbidx, index;
+       size_t sbidx, index, bytes_left_in_page;
        struct lttng_kernel_ring_buffer_backend_pages *rpages;
        unsigned long sb_bindex, id;
 
        do {
-               len -= pagecpy;
-               offset += pagecpy;
                sbidx = offset >> chanb->subbuf_size_order;
                index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT;
 
@@ -634,7 +628,7 @@ void _lib_ring_buffer_memset(struct lttng_kernel_ring_buffer_backend *bufb,
                 */
                CHAN_WARN_ON(chanb, offset >= chanb->buf_size);
 
-               pagecpy = min_t(size_t, len, PAGE_SIZE - (offset & ~PAGE_MASK));
+               bytes_left_in_page = min_t(size_t, len, PAGE_SIZE - (offset & ~PAGE_MASK));
                id = bufb->buf_wsb[sbidx].id;
                sb_bindex = subbuffer_id_get_index(config, id);
                rpages = bufb->array[sb_bindex];
@@ -642,8 +636,10 @@ void _lib_ring_buffer_memset(struct lttng_kernel_ring_buffer_backend *bufb,
                             && subbuffer_id_is_noref(config, id));
                lib_ring_buffer_do_memset(rpages->p[index].virt
                                          + (offset & ~PAGE_MASK),
-                                         c, pagecpy);
-       } while (unlikely(len != pagecpy));
+                                         c, bytes_left_in_page);
+               len -= bytes_left_in_page;
+               offset += bytes_left_in_page;
+       } while (unlikely(len));
 }
 EXPORT_SYMBOL_GPL(_lib_ring_buffer_memset);
 
@@ -812,28 +808,22 @@ EXPORT_SYMBOL_GPL(_lib_ring_buffer_pstrcpy);
  * @offset : offset within the buffer
  * @src : source address
  * @len : length to write
- * @pagecpy : page size copied so far
  *
  * This function deals with userspace pointers, it should never be called
  * directly without having the src pointer checked with access_ok()
  * previously.
  */
 void _lib_ring_buffer_copy_from_user_inatomic(struct lttng_kernel_ring_buffer_backend *bufb,
-                                     size_t offset,
-                                     const void __user *src, size_t len,
-                                     size_t pagecpy)
+                                     size_t offset, const void __user *src, size_t len)
 {
        struct channel_backend *chanb = &bufb->chan->backend;
        const struct lttng_kernel_ring_buffer_config *config = &chanb->config;
-       size_t sbidx, index;
+       size_t sbidx, index, bytes_left_in_page;
        struct lttng_kernel_ring_buffer_backend_pages *rpages;
        unsigned long sb_bindex, id;
        int ret;
 
        do {
-               len -= pagecpy;
-               src += pagecpy;
-               offset += pagecpy;
                sbidx = offset >> chanb->subbuf_size_order;
                index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT;
 
@@ -843,7 +833,7 @@ void _lib_ring_buffer_copy_from_user_inatomic(struct lttng_kernel_ring_buffer_ba
                 */
                CHAN_WARN_ON(chanb, offset >= chanb->buf_size);
 
-               pagecpy = min_t(size_t, len, PAGE_SIZE - (offset & ~PAGE_MASK));
+               bytes_left_in_page = min_t(size_t, len, PAGE_SIZE - (offset & ~PAGE_MASK));
                id = bufb->buf_wsb[sbidx].id;
                sb_bindex = subbuffer_id_get_index(config, id);
                rpages = bufb->array[sb_bindex];
@@ -851,13 +841,16 @@ void _lib_ring_buffer_copy_from_user_inatomic(struct lttng_kernel_ring_buffer_ba
                                && subbuffer_id_is_noref(config, id));
                ret = lib_ring_buffer_do_copy_from_user_inatomic(rpages->p[index].virt
                                                        + (offset & ~PAGE_MASK),
-                                                       src, pagecpy) != 0;
+                                                       src, bytes_left_in_page) != 0;
                if (ret > 0) {
                        /* Copy failed. */
-                       _lib_ring_buffer_memset(bufb, offset, 0, len, 0);
+                       _lib_ring_buffer_memset(bufb, offset, 0, len);
                        break; /* stop copy */
                }
-       } while (unlikely(len != pagecpy));
+               len -= bytes_left_in_page;
+               src += bytes_left_in_page;
+               offset += bytes_left_in_page;
+       } while (unlikely(len));
 }
 EXPORT_SYMBOL_GPL(_lib_ring_buffer_copy_from_user_inatomic);
 
@@ -1042,7 +1035,7 @@ size_t lib_ring_buffer_read(struct lttng_kernel_ring_buffer_backend *bufb, size_
 {
        struct channel_backend *chanb = &bufb->chan->backend;
        const struct lttng_kernel_ring_buffer_config *config = &chanb->config;
-       size_t index, pagecpy, orig_len;
+       size_t index, bytes_left_in_page, orig_len;
        struct lttng_kernel_ring_buffer_backend_pages *rpages;
        unsigned long sb_bindex, id;
 
@@ -1052,19 +1045,19 @@ size_t lib_ring_buffer_read(struct lttng_kernel_ring_buffer_backend *bufb, size_
        if (unlikely(!len))
                return 0;
        for (;;) {
-               pagecpy = min_t(size_t, len, PAGE_SIZE - (offset & ~PAGE_MASK));
+               bytes_left_in_page = min_t(size_t, len, PAGE_SIZE - (offset & ~PAGE_MASK));
                id = bufb->buf_rsb.id;
                sb_bindex = subbuffer_id_get_index(config, id);
                rpages = bufb->array[sb_bindex];
                CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE
                             && subbuffer_id_is_noref(config, id));
                memcpy(dest, rpages->p[index].virt + (offset & ~PAGE_MASK),
-                      pagecpy);
-               len -= pagecpy;
+                      bytes_left_in_page);
+               len -= bytes_left_in_page;
                if (likely(!len))
                        break;
-               dest += pagecpy;
-               offset += pagecpy;
+               dest += bytes_left_in_page;
+               offset += bytes_left_in_page;
                index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT;
                /*
                 * Underlying layer should never ask for reads across
@@ -1094,7 +1087,7 @@ int __lib_ring_buffer_copy_to_user(struct lttng_kernel_ring_buffer_backend *bufb
        struct channel_backend *chanb = &bufb->chan->backend;
        const struct lttng_kernel_ring_buffer_config *config = &chanb->config;
        size_t index;
-       ssize_t pagecpy;
+       ssize_t bytes_left_in_page;
        struct lttng_kernel_ring_buffer_backend_pages *rpages;
        unsigned long sb_bindex, id;
 
@@ -1103,7 +1096,7 @@ int __lib_ring_buffer_copy_to_user(struct lttng_kernel_ring_buffer_backend *bufb
        if (unlikely(!len))
                return 0;
        for (;;) {
-               pagecpy = min_t(size_t, len, PAGE_SIZE - (offset & ~PAGE_MASK));
+               bytes_left_in_page = min_t(size_t, len, PAGE_SIZE - (offset & ~PAGE_MASK));
                id = bufb->buf_rsb.id;
                sb_bindex = subbuffer_id_get_index(config, id);
                rpages = bufb->array[sb_bindex];
@@ -1111,13 +1104,13 @@ int __lib_ring_buffer_copy_to_user(struct lttng_kernel_ring_buffer_backend *bufb
                             && subbuffer_id_is_noref(config, id));
                if (__copy_to_user(dest,
                               rpages->p[index].virt + (offset & ~PAGE_MASK),
-                              pagecpy))
+                              bytes_left_in_page))
                        return -EFAULT;
-               len -= pagecpy;
+               len -= bytes_left_in_page;
                if (likely(!len))
                        break;
-               dest += pagecpy;
-               offset += pagecpy;
+               dest += bytes_left_in_page;
+               offset += bytes_left_in_page;
                index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT;
                /*
                 * Underlying layer should never ask for reads across
@@ -1146,7 +1139,7 @@ int lib_ring_buffer_read_cstr(struct lttng_kernel_ring_buffer_backend *bufb, siz
        struct channel_backend *chanb = &bufb->chan->backend;
        const struct lttng_kernel_ring_buffer_config *config = &chanb->config;
        size_t index;
-       ssize_t pagecpy, pagelen, strpagelen, orig_offset;
+       ssize_t bytes_left_in_page, pagelen, strpagelen, orig_offset;
        char *str;
        struct lttng_kernel_ring_buffer_backend_pages *rpages;
        unsigned long sb_bindex, id;
@@ -1166,12 +1159,12 @@ int lib_ring_buffer_read_cstr(struct lttng_kernel_ring_buffer_backend *bufb, siz
                pagelen = PAGE_SIZE - (offset & ~PAGE_MASK);
                strpagelen = strnlen(str, pagelen);
                if (len) {
-                       pagecpy = min_t(size_t, len, strpagelen);
+                       bytes_left_in_page = min_t(size_t, len, strpagelen);
                        if (dest) {
-                               memcpy(dest, str, pagecpy);
-                               dest += pagecpy;
+                               memcpy(dest, str, bytes_left_in_page);
+                               dest += bytes_left_in_page;
                        }
-                       len -= pagecpy;
+                       len -= bytes_left_in_page;
                }
                offset += strpagelen;
                index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT;