All of lore.kernel.org
 help / color / mirror / Atom feed
From: Nathan Lynch <nathanl@linux.ibm.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: mpe@ellerman.id.au, linux-kernel@vger.kernel.org,
	gregkh@linuxfoundation.org, jirislaby@kernel.org
Subject: [PATCH] powerpc/udbg_hvc: retry putc on -EAGAIN
Date: Fri, 14 May 2021 16:44:22 -0500	[thread overview]
Message-ID: <20210514214422.3019105-1-nathanl@linux.ibm.com> (raw)

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


WARNING: multiple messages have this Message-ID
From: Nathan Lynch <nathanl@linux.ibm.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: jirislaby@kernel.org, linux-kernel@vger.kernel.org,
	gregkh@linuxfoundation.org
Subject: [PATCH] powerpc/udbg_hvc: retry putc on -EAGAIN
Date: Fri, 14 May 2021 16:44:22 -0500	[thread overview]
Message-ID: <20210514214422.3019105-1-nathanl@linux.ibm.com> (raw)

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


             reply	other threads:[~2021-05-14 21:44 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-14 21:44 Nathan Lynch [this message]
2021-05-14 21:44 ` [PATCH] powerpc/udbg_hvc: retry putc on -EAGAIN 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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210514214422.3019105-1-nathanl@linux.ibm.com \
    --to=nathanl@linux.ibm.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=jirislaby@kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=mpe@ellerman.id.au \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.