From: Darrick J. Wong <[email protected]> Experimentally fix some problems with stdio_redirect_vprintf by creating a MOO variant with which we can experiment. We can't do a GFP_KERNEL allocation while holding the spinlock, and I don't like how the printf function can silently truncate the output if memory allocation fails.
Signed-off-by: Darrick J. Wong <[email protected]> Signed-off-by: Kent Overstreet <[email protected]> --- include/linux/thread_with_file.h | 4 +-- lib/thread_with_file.c | 55 ++++++++++++++++++++++++++------------ 2 files changed, 39 insertions(+), 20 deletions(-) diff --git a/include/linux/thread_with_file.h b/include/linux/thread_with_file.h index 5f7e85bc8322b..7b133a15d3540 100644 --- a/include/linux/thread_with_file.h +++ b/include/linux/thread_with_file.h @@ -68,7 +68,7 @@ int run_thread_with_stdout(struct thread_with_stdio *, int stdio_redirect_read(struct stdio_redirect *, char *, size_t); int stdio_redirect_readline(struct stdio_redirect *, char *, size_t); -__printf(3, 0) void stdio_redirect_vprintf(struct stdio_redirect *, bool, const char *, va_list); -__printf(3, 4) void stdio_redirect_printf(struct stdio_redirect *, bool, const char *, ...); +__printf(3, 0) ssize_t stdio_redirect_vprintf(struct stdio_redirect *, bool, const char *, va_list); +__printf(3, 4) ssize_t stdio_redirect_printf(struct stdio_redirect *, bool, const char *, ...); #endif /* _LINUX_THREAD_WITH_FILE_H */ diff --git a/lib/thread_with_file.c b/lib/thread_with_file.c index 71028611b8d59..70a805ef017f9 100644 --- a/lib/thread_with_file.c +++ b/lib/thread_with_file.c @@ -108,49 +108,68 @@ int stdio_redirect_readline(struct stdio_redirect *stdio, char *ubuf, size_t len EXPORT_SYMBOL_GPL(stdio_redirect_readline); __printf(3, 0) -static void darray_vprintf(darray_char *out, gfp_t gfp, const char *fmt, va_list args) +static ssize_t darray_vprintf(darray_char *out, gfp_t gfp, const char *fmt, va_list args) { - size_t len; + ssize_t ret; do { va_list args2; + size_t len; + va_copy(args2, args); - len = vsnprintf(out->data + out->nr, darray_room(*out), fmt, args2); - } while (len + 1 > darray_room(*out) && !darray_make_room_gfp(out, len + 1, gfp)); + if (len + 1 <= darray_room(*out)) { + out->nr += len; + return len; + } - out->nr += min(len, darray_room(*out)); + ret = darray_make_room_gfp(out, len + 1, gfp); + } while (ret == 0); + + return ret; } -void stdio_redirect_vprintf(struct stdio_redirect *stdio, bool nonblocking, - const char *fmt, va_list args) +ssize_t stdio_redirect_vprintf(struct stdio_redirect *stdio, bool nonblocking, + const char *fmt, va_list args) { struct stdio_buf *buf = &stdio->output; unsigned long flags; + ssize_t ret; - if (!nonblocking) - wait_event(buf->wait, stdio_redirect_has_output_space(stdio)); - else if (!stdio_redirect_has_output_space(stdio)) - return; - if (stdio->done) - return; - +again: spin_lock_irqsave(&buf->lock, flags); - darray_vprintf(&buf->buf, nonblocking ? GFP_NOWAIT : GFP_KERNEL, fmt, args); + ret = darray_vprintf(&buf->buf, GFP_NOWAIT, fmt, args); spin_unlock_irqrestore(&buf->lock, flags); + if (ret < 0) { + if (nonblocking) + return -EAGAIN; + + ret = wait_event_interruptible(buf->wait, + stdio_redirect_has_output_space(stdio)); + if (ret) + return ret; + goto again; + } + wake_up(&buf->wait); + return ret; + } EXPORT_SYMBOL_GPL(stdio_redirect_vprintf); -void stdio_redirect_printf(struct stdio_redirect *stdio, bool nonblocking, - const char *fmt, ...) +ssize_t stdio_redirect_printf(struct stdio_redirect *stdio, bool nonblocking, + const char *fmt, ...) { va_list args; + ssize_t ret; + va_start(args, fmt); - stdio_redirect_vprintf(stdio, nonblocking, fmt, args); + ret = stdio_redirect_vprintf(stdio, nonblocking, fmt, args); va_end(args); + + return ret; } EXPORT_SYMBOL_GPL(stdio_redirect_printf);
