* [PATCH stable] serial: samsung: Reorder the sequence of clock control when call s3c24xx_serial_set_termios()
@ 2016-05-30 14:19 Krzysztof Kozlowski
0 siblings, 0 replies; 4+ messages in thread
From: Krzysztof Kozlowski @ 2016-05-30 14:19 UTC (permalink / raw)
To: Greg Kroah-Hartman, Jiri Slaby, linux-serial, linux-kernel
Cc: Chanwoo Choi, Bartlomiej Zolnierkiewicz, stable, Krzysztof Kozlowski
From: Chanwoo Choi <cw00.choi@samsung.com>
commit b8995f527aac143e83d3900ff39357651ea4e0f6 upstream.
This patch fixes the broken serial log when changing the clock source
of uart device. Before disabling the original clock source, this patch
enables the new clock source to protect the clock off state for a split second.
[k.kozlowski]:
On SMP systems this opens a short time window when both clocks (old and
new) are disabled and a second thread uses TTY/UART. This leads to
broken log or imprecise external abort (on one of ARM64 boards):
Unhandled fault: synchronous external abort (0x96000210) at 0xffffff8008080008
Internal error: : 96000210 [#1] PREEMPT SMP
[<ffffff8008427634>] s3c24xx_serial_console_putchar+0x8/0x64
[<ffffff8008427fa0>] s3c24xx_serial_console_write+0x30/0x38
[<ffffff80080f4e68>] call_console_drivers.constprop.22+0x100/0x108
[<ffffff80080f5d34>] console_unlock+0x504/0x58c
[<ffffff80080f6088>] vprintk_emit+0x2cc/0x478
[<ffffff80080f63ac>] vprintk_default+0x38/0x40
[<ffffff800814beb4>] printk+0xac/0xb8
[<ffffff800812f20c>] audit_printk_skb+0x68/0x6c
[<ffffff800812f4ec>] audit_log_end+0x13c/0x188
[<ffffff8008306064>] common_lsm_audit+0xb4/0x618
[<ffffff8008302cb0>] smack_log+0xe8/0x10c
[<ffffff8008303408>] smk_tskacc+0x8c/0xa4
[<ffffff800830344c>] smk_curacc+0x2c/0x34
[<ffffff800830066c>] smack_inode_permission+0x60/0x70
[<ffffff80082fb7d8>] security_inode_permission+0x58/0x80
[<ffffff80081c15a4>] __inode_permission+0x40/0xa0
[<ffffff80081c1618>] inode_permission+0x14/0x4c
[<ffffff80081c1e4c>] may_open+0x5c/0x10c
[<ffffff80081c47e8>] path_openat+0x13c/0xec8
[<ffffff80081c64f8>] do_filp_open+0x64/0xc0
[<ffffff80081b5ea0>] do_sys_open+0x144/0x208
[<ffffff80081b5f9c>] SyS_openat+0x10/0x18
[<ffffff8008085ecc>] __sys_trace_return+0x0/0x4
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Reviewed-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: <stable@vger.kernel.org>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
[k.kozlowski: Backport to stable, update commit msg]
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
---
The original Samsung serial driver was broken so this should be
backported as far as possible including the 2.6.12. :)
---
drivers/tty/serial/samsung.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c
index ac7f8df54406..99bb23161dd6 100644
--- a/drivers/tty/serial/samsung.c
+++ b/drivers/tty/serial/samsung.c
@@ -1271,6 +1271,8 @@ static void s3c24xx_serial_set_termios(struct uart_port *port,
/* check to see if we need to change clock source */
if (ourport->baudclk != clk) {
+ clk_prepare_enable(clk);
+
s3c24xx_serial_setsource(port, clk_sel);
if (!IS_ERR(ourport->baudclk)) {
@@ -1278,8 +1280,6 @@ static void s3c24xx_serial_set_termios(struct uart_port *port,
ourport->baudclk = ERR_PTR(-EINVAL);
}
- clk_prepare_enable(clk);
-
ourport->baudclk = clk;
ourport->baudclk_rate = clk ? clk_get_rate(clk) : 0;
}
--
1.9.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH stable] serial: samsung: Reorder the sequence of clock control when call s3c24xx_serial_set_termios()
2016-05-02 18:24 ` Greg Kroah-Hartman
@ 2016-05-03 10:06 ` Krzysztof Kozlowski
0 siblings, 0 replies; 4+ messages in thread
From: Krzysztof Kozlowski @ 2016-05-03 10:06 UTC (permalink / raw)
To: Greg Kroah-Hartman
Cc: Krzysztof Kozlowski, Jiri Slaby, linux-serial, linux-kernel,
Marek Szyprowski, Chanwoo Choi, stable,
Bartlomiej Zolnierkiewicz
On Mon, May 02, 2016 at 11:24:59AM -0700, Greg Kroah-Hartman wrote:
> On Mon, May 02, 2016 at 02:25:07PM +0200, Krzysztof Kozlowski wrote:
> > From: Chanwoo Choi <cw00.choi@samsung.com>
> >
> > commit b8995f527aac143e83d3900ff39357651ea4e0f6 upstream
>
> This isn't in Linus's tree yet, so we can't take this into any -stable
> trees yet. Please wait for that to happen, can you resend this when
> that happens?
Of course, no problem. I will resend this.
Best regards,
Krzysztof
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH stable] serial: samsung: Reorder the sequence of clock control when call s3c24xx_serial_set_termios()
2016-05-02 12:25 Krzysztof Kozlowski
@ 2016-05-02 18:24 ` Greg Kroah-Hartman
2016-05-03 10:06 ` Krzysztof Kozlowski
0 siblings, 1 reply; 4+ messages in thread
From: Greg Kroah-Hartman @ 2016-05-02 18:24 UTC (permalink / raw)
To: Krzysztof Kozlowski
Cc: Jiri Slaby, linux-serial, linux-kernel, Marek Szyprowski,
Chanwoo Choi, stable, Bartlomiej Zolnierkiewicz
On Mon, May 02, 2016 at 02:25:07PM +0200, Krzysztof Kozlowski wrote:
> From: Chanwoo Choi <cw00.choi@samsung.com>
>
> commit b8995f527aac143e83d3900ff39357651ea4e0f6 upstream
This isn't in Linus's tree yet, so we can't take this into any -stable
trees yet. Please wait for that to happen, can you resend this when
that happens?
thanks,
greg k-h
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH stable] serial: samsung: Reorder the sequence of clock control when call s3c24xx_serial_set_termios()
@ 2016-05-02 12:25 Krzysztof Kozlowski
2016-05-02 18:24 ` Greg Kroah-Hartman
0 siblings, 1 reply; 4+ messages in thread
From: Krzysztof Kozlowski @ 2016-05-02 12:25 UTC (permalink / raw)
To: Greg Kroah-Hartman, Jiri Slaby, linux-serial, linux-kernel
Cc: Marek Szyprowski, Chanwoo Choi, stable, Krzysztof Kozlowski,
Bartlomiej Zolnierkiewicz
From: Chanwoo Choi <cw00.choi@samsung.com>
commit b8995f527aac143e83d3900ff39357651ea4e0f6 upstream
This patch fixes the broken serial log when changing the clock source
of uart device. Before disabling the original clock source, this patch
enables the new clock source to protect the clock off state for a split second.
[k.kozlowski]:
On SMP systems this opens a short time window when both clocks (old and
new) are disabled and a second thread uses TTY/UART. This leads to
broken log or imprecise external abort (on one of ARM64 boards):
Unhandled fault: synchronous external abort (0x96000210) at 0xffffff8008080008
Internal error: : 96000210 [#1] PREEMPT SMP
[<ffffff8008427634>] s3c24xx_serial_console_putchar+0x8/0x64
[<ffffff8008427fa0>] s3c24xx_serial_console_write+0x30/0x38
[<ffffff80080f4e68>] call_console_drivers.constprop.22+0x100/0x108
[<ffffff80080f5d34>] console_unlock+0x504/0x58c
[<ffffff80080f6088>] vprintk_emit+0x2cc/0x478
[<ffffff80080f63ac>] vprintk_default+0x38/0x40
[<ffffff800814beb4>] printk+0xac/0xb8
[<ffffff800812f20c>] audit_printk_skb+0x68/0x6c
[<ffffff800812f4ec>] audit_log_end+0x13c/0x188
[<ffffff8008306064>] common_lsm_audit+0xb4/0x618
[<ffffff8008302cb0>] smack_log+0xe8/0x10c
[<ffffff8008303408>] smk_tskacc+0x8c/0xa4
[<ffffff800830344c>] smk_curacc+0x2c/0x34
[<ffffff800830066c>] smack_inode_permission+0x60/0x70
[<ffffff80082fb7d8>] security_inode_permission+0x58/0x80
[<ffffff80081c15a4>] __inode_permission+0x40/0xa0
[<ffffff80081c1618>] inode_permission+0x14/0x4c
[<ffffff80081c1e4c>] may_open+0x5c/0x10c
[<ffffff80081c47e8>] path_openat+0x13c/0xec8
[<ffffff80081c64f8>] do_filp_open+0x64/0xc0
[<ffffff80081b5ea0>] do_sys_open+0x144/0x208
[<ffffff80081b5f9c>] SyS_openat+0x10/0x18
[<ffffff8008085ecc>] __sys_trace_return+0x0/0x4
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Reviewed-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: <stable@vger.kernel.org>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
[k.kozlowski: Backport to stable, update commit msg]
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
---
The original Samsung serial driver was broken so this should be
backported as far as possible including the 2.6.12. :)
---
drivers/tty/serial/samsung.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c
index ac7f8df54406..99bb23161dd6 100644
--- a/drivers/tty/serial/samsung.c
+++ b/drivers/tty/serial/samsung.c
@@ -1271,6 +1271,8 @@ static void s3c24xx_serial_set_termios(struct uart_port *port,
/* check to see if we need to change clock source */
if (ourport->baudclk != clk) {
+ clk_prepare_enable(clk);
+
s3c24xx_serial_setsource(port, clk_sel);
if (!IS_ERR(ourport->baudclk)) {
@@ -1278,8 +1280,6 @@ static void s3c24xx_serial_set_termios(struct uart_port *port,
ourport->baudclk = ERR_PTR(-EINVAL);
}
- clk_prepare_enable(clk);
-
ourport->baudclk = clk;
ourport->baudclk_rate = clk ? clk_get_rate(clk) : 0;
}
--
1.9.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
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2016-05-02 12:25 Krzysztof Kozlowski
2016-05-02 18:24 ` Greg Kroah-Hartman
2016-05-03 10:06 ` Krzysztof Kozlowski
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