From 14f693eeb5b16bc47ffa38d8b8838a654aedd53f Mon Sep 17 00:00:00 2001 From: Jeremy Kerr Date: Thu, 16 Oct 2008 10:51:46 +1100 Subject: [PATCH] powerpc/spufs: Don't require full buffer in switch_log read Currently, read() on the sputrace log will block until the read buffer is full. This makes it difficult to retrieve the end of the buffer, as the user will need to read with the right-sized buffer. In a similar method as 91553a1b5e0df006a3573a88d98ee7cd48a3818a, this change makes the switch_log return if there has already been data read. Signed-off-by: Jeremy Kerr --- arch/powerpc/platforms/cell/spufs/file.c | 46 ++++++++++++++---------- 1 file changed, 27 insertions(+), 19 deletions(-) diff --git a/arch/powerpc/platforms/cell/spufs/file.c b/arch/powerpc/platforms/cell/spufs/file.c index adb5abb9af5d..f139cd8b594d 100644 --- a/arch/powerpc/platforms/cell/spufs/file.c +++ b/arch/powerpc/platforms/cell/spufs/file.c @@ -2503,30 +2503,38 @@ static ssize_t spufs_switch_log_read(struct file *file, char __user *buf, char tbuf[128]; int width; - if (file->f_flags & O_NONBLOCK) { - if (spufs_switch_log_used(ctx) == 0) { + if (spufs_switch_log_used(ctx) == 0) { + if (cnt > 0) { + /* If there's data ready to go, we can + * just return straight away */ + break; + + } else if (file->f_flags & O_NONBLOCK) { error = -EAGAIN; break; + + } else { + /* spufs_wait will drop the mutex and + * re-acquire, but since we're in read(), the + * file cannot be _released (and so + * ctx->switch_log is stable). + */ + error = spufs_wait(ctx->switch_log->wait, + spufs_switch_log_used(ctx) > 0); + + /* On error, spufs_wait returns without the + * state mutex held */ + if (error) + return error; + + /* We may have had entries read from underneath + * us while we dropped the mutex in spufs_wait, + * so re-check */ + if (spufs_switch_log_used(ctx) == 0) + continue; } - } else { - /* spufs_wait will drop the mutex and re-acquire, - * but since we're in read(), the file cannot be - * _released (and so ctx->switch_log is stable). - */ - error = spufs_wait(ctx->switch_log->wait, - spufs_switch_log_used(ctx) > 0); - - /* On error, spufs_wait returns without the - * state mutex held */ - if (error) - return error; } - /* We may have had entries read from underneath us while we - * dropped the mutex in spufs_wait, so re-check */ - if (ctx->switch_log->head == ctx->switch_log->tail) - continue; - width = switch_log_sprint(ctx, tbuf, sizeof(tbuf)); if (width < len) ctx->switch_log->tail =