diff options
| -rw-r--r-- | fs/pipe.c | 28 | ||||
| -rw-r--r-- | include/linux/pipe_fs_i.h | 7 | ||||
| -rw-r--r-- | kernel/watch_queue.c | 2 | ||||
| -rw-r--r-- | samples/watch_queue/watch_test.c | 3 |
4 files changed, 40 insertions, 0 deletions
diff --git a/fs/pipe.c b/fs/pipe.c index 0f9fd897ceb5..620a113f92eb 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -314,6 +314,30 @@ pipe_read(struct kiocb *iocb, struct iov_iter *to) unsigned int tail = pipe->tail; unsigned int mask = pipe->ring_size - 1; +#ifdef CONFIG_WATCH_QUEUE + if (pipe->note_loss) { + struct watch_notification n; + + if (total_len < 8) { + if (ret == 0) + ret = -ENOBUFS; + break; + } + + n.type = WATCH_TYPE_META; + n.subtype = WATCH_META_LOSS_NOTIFICATION; + n.info = watch_sizeof(n); + if (copy_to_iter(&n, sizeof(n), to) != sizeof(n)) { + if (ret == 0) + ret = -EFAULT; + break; + } + ret += sizeof(n); + total_len -= sizeof(n); + pipe->note_loss = false; + } +#endif + if (!pipe_empty(head, tail)) { struct pipe_buffer *buf = &pipe->bufs[tail & mask]; size_t chars = buf->len; @@ -355,6 +379,10 @@ pipe_read(struct kiocb *iocb, struct iov_iter *to) if (!buf->len) { pipe_buf_release(pipe, buf); spin_lock_irq(&pipe->rd_wait.lock); +#ifdef CONFIG_WATCH_QUEUE + if (buf->flags & PIPE_BUF_FLAG_LOSS) + pipe->note_loss = true; +#endif tail++; pipe->tail = tail; spin_unlock_irq(&pipe->rd_wait.lock); diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h index eaff59a2f074..6626f511de6f 100644 --- a/include/linux/pipe_fs_i.h +++ b/include/linux/pipe_fs_i.h @@ -9,6 +9,9 @@ #define PIPE_BUF_FLAG_GIFT 0x04 /* page is a gift */ #define PIPE_BUF_FLAG_PACKET 0x08 /* read() as a packet */ #define PIPE_BUF_FLAG_WHOLE 0x10 /* read() must return entire buffer or error */ +#ifdef CONFIG_WATCH_QUEUE +#define PIPE_BUF_FLAG_LOSS 0x20 /* Message loss happened after this buffer */ +#endif /** * struct pipe_buffer - a linux kernel pipe buffer @@ -34,6 +37,7 @@ struct pipe_buffer { * @wr_wait: writer wait point in case of full pipe * @head: The point of buffer production * @tail: The point of buffer consumption + * @note_loss: The next read() should insert a data-lost message * @max_usage: The maximum number of slots that may be used in the ring * @ring_size: total number of buffers (should be a power of 2) * @nr_accounted: The amount this pipe accounts for in user->pipe_bufs @@ -56,6 +60,9 @@ struct pipe_inode_info { unsigned int tail; unsigned int max_usage; unsigned int ring_size; +#ifdef CONFIG_WATCH_QUEUE + bool note_loss; +#endif unsigned int nr_accounted; unsigned int readers; unsigned int writers; diff --git a/kernel/watch_queue.c b/kernel/watch_queue.c index ad64ea300f6d..9a9699c06709 100644 --- a/kernel/watch_queue.c +++ b/kernel/watch_queue.c @@ -132,6 +132,8 @@ out: return done; lost: + buf = &pipe->bufs[(head - 1) & mask]; + buf->flags |= PIPE_BUF_FLAG_LOSS; goto out; } diff --git a/samples/watch_queue/watch_test.c b/samples/watch_queue/watch_test.c index 8628b4c5d567..46e618a897fe 100644 --- a/samples/watch_queue/watch_test.c +++ b/samples/watch_queue/watch_test.c @@ -120,6 +120,9 @@ static void consumer(int fd) (n.n.info & WATCH_INFO_ID) >> WATCH_INFO_ID__SHIFT); break; + case WATCH_META_LOSS_NOTIFICATION: + printf("-- LOSS --\n"); + break; default: printf("other meta record\n"); break; |