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* [PATCH] powerpc/udbg_hvc: retry putc on -EAGAIN
@ 2021-05-14 21:44 ` Nathan Lynch
  0 siblings, 0 replies; 9+ messages in thread
From: Nathan Lynch @ 2021-05-14 21:44 UTC (permalink / raw)
  To: linuxppc-dev; +Cc: mpe, linux-kernel, gregkh, jirislaby

hvterm_raw_put_chars() calls hvc_put_chars(), which may return -EAGAIN
when the underlying hcall returns a "busy" status, but udbg_hvc_putc()
doesn't handle this. When using xmon on a PowerVM guest, this can
result in incomplete or garbled output when printing relatively large
amounts of data quickly, such as when dumping the kernel log buffer.

Call again on -EAGAIN.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 drivers/tty/hvc/hvc_vio.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/hvc/hvc_vio.c b/drivers/tty/hvc/hvc_vio.c
index 798f27f40cc2..76d2a7038095 100644
--- a/drivers/tty/hvc/hvc_vio.c
+++ b/drivers/tty/hvc/hvc_vio.c
@@ -249,7 +249,7 @@ static void udbg_hvc_putc(char c)
 			count = hvterm_hvsi_put_chars(0, &c, 1);
 			break;
 		}
-	} while(count == 0);
+	} while(count == 0 || count == -EAGAIN);
 }
 
 static int udbg_hvc_getc_poll(void)
-- 
2.30.2


^ permalink raw reply related	[flat|nested] 9+ messages in thread

end of thread, other threads:[~2021-06-06 12:13 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-05-14 21:44 [PATCH] powerpc/udbg_hvc: retry putc on -EAGAIN Nathan Lynch
2021-05-14 21:44 ` Nathan Lynch
2021-05-21 12:47 ` Greg KH
2021-05-21 12:47   ` Greg KH
2021-05-23 10:51   ` Michael Ellerman
2021-05-23 10:51     ` Michael Ellerman
2021-05-27 11:10     ` Greg KH
2021-05-27 11:10       ` Greg KH
2021-06-06 12:08 ` Michael Ellerman

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