* [PATCH] tty: serial: fsl_lpuart: disable dma rx/tx use flags in lpuart_dma_shutdown
@ 2022-09-20 11:17 Sherry Sun
2022-09-20 12:25 ` Ilpo Järvinen
2022-09-21 8:45 ` Ilpo Järvinen
0 siblings, 2 replies; 6+ messages in thread
From: Sherry Sun @ 2022-09-20 11:17 UTC (permalink / raw)
To: gregkh, jirislaby, bhuvanchandra.dv; +Cc: linux-serial, linux-kernel, linux-imx
lpuart_dma_shutdown tears down lpuart dma, but lpuart_flush_buffer can
still occur which in turn tries to access dma apis if lpuart_dma_tx_use
flag is true. At this point since dma is torn down, these dma apis can
abort. Set lpuart_dma_tx_use and the corresponding rx flag
lpuart_dma_rx_use to false in lpuart_dma_shutdown so that dmas are not
accessed after they are relinquished.
Otherwise, when try to kill btattach, kernel may panic. This patch may
fix this issue.
root@imx8ulpevk:~# btattach -B /dev/ttyLP2 -S 115200
^C[ 90.182296] Internal error: synchronous external abort: 96000210 [#1] PREEMPT SMP
[ 90.189806] Modules linked in: moal(O) mlan(O)
[ 90.194258] CPU: 0 PID: 503 Comm: btattach Tainted: G O 5.15.32-06136-g34eecdf2f9e4 #37
[ 90.203554] Hardware name: NXP i.MX8ULP 9X9 EVK (DT)
[ 90.208513] pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 90.215470] pc : fsl_edma3_disable_request+0x8/0x60
[ 90.220358] lr : fsl_edma3_terminate_all+0x34/0x20c
[ 90.225237] sp : ffff800013f0bac0
[ 90.228548] x29: ffff800013f0bac0 x28: 0000000000000001 x27: ffff000008404800
[ 90.235681] x26: ffff000008404960 x25: ffff000008404a08 x24: ffff000008404a00
[ 90.242813] x23: ffff000008404a60 x22: 0000000000000002 x21: 0000000000000000
[ 90.249946] x20: ffff800013f0baf8 x19: ffff00000559c800 x18: 0000000000000000
[ 90.257078] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
[ 90.264211] x14: 0000000000000003 x13: 0000000000000000 x12: 0000000000000040
[ 90.271344] x11: ffff00000600c248 x10: ffff800013f0bb10 x9 : ffff000057bcb090
[ 90.278477] x8 : fffffc0000241a08 x7 : ffff00000534ee00 x6 : ffff000008404804
[ 90.285609] x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff0000055b3480
[ 90.292742] x2 : ffff8000135c0000 x1 : ffff00000534ee00 x0 : ffff00000559c800
[ 90.299876] Call trace:
[ 90.302321] fsl_edma3_disable_request+0x8/0x60
[ 90.306851] lpuart_flush_buffer+0x40/0x160
[ 90.311037] uart_flush_buffer+0x88/0x120
[ 90.315050] tty_driver_flush_buffer+0x20/0x30
[ 90.319496] hci_uart_flush+0x44/0x90
[ 90.323162] +0x34/0x12c
[ 90.327253] tty_ldisc_close+0x38/0x70
[ 90.331005] tty_ldisc_release+0xa8/0x190
[ 90.335018] tty_release_struct+0x24/0x8c
[ 90.339022] tty_release+0x3ec/0x4c0
[ 90.342593] __fput+0x70/0x234
[ 90.345652] ____fput+0x14/0x20
[ 90.348790] task_work_run+0x84/0x17c
[ 90.352455] do_exit+0x310/0x96c
[ 90.355688] do_group_exit+0x3c/0xa0
[ 90.359259] __arm64_sys_exit_group+0x1c/0x20
[ 90.363609] invoke_syscall+0x48/0x114
[ 90.367362] el0_svc_common.constprop.0+0xd4/0xfc
[ 90.372068] do_el0_svc+0x2c/0x94
[ 90.375379] el0_svc+0x28/0x80
[ 90.378438] el0t_64_sync_handler+0xa8/0x130
[ 90.382711] el0t_64_sync+0x1a0/0x1a4
[ 90.386376] Code: 17ffffda d503201f d503233f f9409802 (b9400041)
[ 90.392467] ---[ end trace 2f60524b4a43f1f6 ]---
[ 90.397073] note: btattach[503] exited with preempt_count 1
[ 90.402636] Fixing recursive fault but reboot is needed!
Fixes: 6250cc30c4c4 ("tty: serial: fsl_lpuart: Use scatter/gather DMA for Tx")
Signed-off-by: Thara Gopinath <tgopinath@microsoft.com>
Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
---
drivers/tty/serial/fsl_lpuart.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index f21915015d67..064bd1f33c21 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -1771,6 +1771,7 @@ static void lpuart_dma_shutdown(struct lpuart_port *sport)
if (sport->lpuart_dma_rx_use) {
del_timer_sync(&sport->lpuart_timer);
lpuart_dma_rx_free(&sport->port);
+ sport->lpuart_dma_rx_use = false;
}
if (sport->lpuart_dma_tx_use) {
@@ -1779,6 +1780,7 @@ static void lpuart_dma_shutdown(struct lpuart_port *sport)
sport->dma_tx_in_progress = false;
dmaengine_terminate_all(sport->dma_tx_chan);
}
+ sport->lpuart_dma_tx_use = false;
}
if (sport->dma_tx_chan)
--
2.17.1
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] tty: serial: fsl_lpuart: disable dma rx/tx use flags in lpuart_dma_shutdown 2022-09-20 11:17 [PATCH] tty: serial: fsl_lpuart: disable dma rx/tx use flags in lpuart_dma_shutdown Sherry Sun @ 2022-09-20 12:25 ` Ilpo Järvinen 2022-09-20 14:04 ` Sherry Sun 2022-09-21 8:45 ` Ilpo Järvinen 1 sibling, 1 reply; 6+ messages in thread From: Ilpo Järvinen @ 2022-09-20 12:25 UTC (permalink / raw) To: Sherry Sun Cc: gregkh, jirislaby, bhuvanchandra.dv, linux-serial, linux-kernel, linux-imx On Tue, 20 Sep 2022, Sherry Sun wrote: > lpuart_dma_shutdown tears down lpuart dma, but lpuart_flush_buffer can > still occur which in turn tries to access dma apis if lpuart_dma_tx_use > flag is true. At this point since dma is torn down, these dma apis can > abort. Set lpuart_dma_tx_use and the corresponding rx flag > lpuart_dma_rx_use to false in lpuart_dma_shutdown so that dmas are not > accessed after they are relinquished. > > Otherwise, when try to kill btattach, kernel may panic. This patch may > fix this issue. > root@imx8ulpevk:~# btattach -B /dev/ttyLP2 -S 115200 > ^C[ 90.182296] Internal error: synchronous external abort: 96000210 [#1] PREEMPT SMP > [ 90.189806] Modules linked in: moal(O) mlan(O) > [ 90.194258] CPU: 0 PID: 503 Comm: btattach Tainted: G O 5.15.32-06136-g34eecdf2f9e4 #37 > [ 90.203554] Hardware name: NXP i.MX8ULP 9X9 EVK (DT) > [ 90.208513] pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--) > [ 90.215470] pc : fsl_edma3_disable_request+0x8/0x60 > [ 90.220358] lr : fsl_edma3_terminate_all+0x34/0x20c > [ 90.225237] sp : ffff800013f0bac0 > [ 90.228548] x29: ffff800013f0bac0 x28: 0000000000000001 x27: ffff000008404800 > [ 90.235681] x26: ffff000008404960 x25: ffff000008404a08 x24: ffff000008404a00 > [ 90.242813] x23: ffff000008404a60 x22: 0000000000000002 x21: 0000000000000000 > [ 90.249946] x20: ffff800013f0baf8 x19: ffff00000559c800 x18: 0000000000000000 > [ 90.257078] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000 > [ 90.264211] x14: 0000000000000003 x13: 0000000000000000 x12: 0000000000000040 > [ 90.271344] x11: ffff00000600c248 x10: ffff800013f0bb10 x9 : ffff000057bcb090 > [ 90.278477] x8 : fffffc0000241a08 x7 : ffff00000534ee00 x6 : ffff000008404804 > [ 90.285609] x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff0000055b3480 > [ 90.292742] x2 : ffff8000135c0000 x1 : ffff00000534ee00 x0 : ffff00000559c800 > [ 90.299876] Call trace: > [ 90.302321] fsl_edma3_disable_request+0x8/0x60 > [ 90.306851] lpuart_flush_buffer+0x40/0x160 > [ 90.311037] uart_flush_buffer+0x88/0x120 > [ 90.315050] tty_driver_flush_buffer+0x20/0x30 > [ 90.319496] hci_uart_flush+0x44/0x90 > [ 90.323162] +0x34/0x12c > [ 90.327253] tty_ldisc_close+0x38/0x70 > [ 90.331005] tty_ldisc_release+0xa8/0x190 > [ 90.335018] tty_release_struct+0x24/0x8c > [ 90.339022] tty_release+0x3ec/0x4c0 > [ 90.342593] __fput+0x70/0x234 > [ 90.345652] ____fput+0x14/0x20 > [ 90.348790] task_work_run+0x84/0x17c > [ 90.352455] do_exit+0x310/0x96c > [ 90.355688] do_group_exit+0x3c/0xa0 > [ 90.359259] __arm64_sys_exit_group+0x1c/0x20 > [ 90.363609] invoke_syscall+0x48/0x114 > [ 90.367362] el0_svc_common.constprop.0+0xd4/0xfc > [ 90.372068] do_el0_svc+0x2c/0x94 > [ 90.375379] el0_svc+0x28/0x80 > [ 90.378438] el0t_64_sync_handler+0xa8/0x130 > [ 90.382711] el0t_64_sync+0x1a0/0x1a4 > [ 90.386376] Code: 17ffffda d503201f d503233f f9409802 (b9400041) > [ 90.392467] ---[ end trace 2f60524b4a43f1f6 ]--- > [ 90.397073] note: btattach[503] exited with preempt_count 1 > [ 90.402636] Fixing recursive fault but reboot is needed! > > Fixes: 6250cc30c4c4 ("tty: serial: fsl_lpuart: Use scatter/gather DMA for Tx") > Signed-off-by: Thara Gopinath <tgopinath@microsoft.com> > Signed-off-by: Sherry Sun <sherry.sun@nxp.com> > --- > drivers/tty/serial/fsl_lpuart.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c > index f21915015d67..064bd1f33c21 100644 > --- a/drivers/tty/serial/fsl_lpuart.c > +++ b/drivers/tty/serial/fsl_lpuart.c > @@ -1771,6 +1771,7 @@ static void lpuart_dma_shutdown(struct lpuart_port *sport) > if (sport->lpuart_dma_rx_use) { > del_timer_sync(&sport->lpuart_timer); > lpuart_dma_rx_free(&sport->port); > + sport->lpuart_dma_rx_use = false; > } > > if (sport->lpuart_dma_tx_use) { > @@ -1779,6 +1780,7 @@ static void lpuart_dma_shutdown(struct lpuart_port *sport) > sport->dma_tx_in_progress = false; > dmaengine_terminate_all(sport->dma_tx_chan); > } > + sport->lpuart_dma_tx_use = false; > } > > if (sport->dma_tx_chan) Isn't it still racy because lpuart_dma_shutdown() is called outside of port's lock? -- i. ^ permalink raw reply [flat|nested] 6+ messages in thread
* RE: [PATCH] tty: serial: fsl_lpuart: disable dma rx/tx use flags in lpuart_dma_shutdown 2022-09-20 12:25 ` Ilpo Järvinen @ 2022-09-20 14:04 ` Sherry Sun 2022-09-21 8:43 ` Ilpo Järvinen 0 siblings, 1 reply; 6+ messages in thread From: Sherry Sun @ 2022-09-20 14:04 UTC (permalink / raw) To: Ilpo Järvinen Cc: gregkh@linuxfoundation.org, jirislaby@kernel.org, bhuvanchandra.dv@toradex.com, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, dl-linux-imx > -----Original Message----- > From: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> > Sent: 2022年9月20日 20:26 > To: Sherry Sun <sherry.sun@nxp.com> > Cc: gregkh@linuxfoundation.org; jirislaby@kernel.org; > bhuvanchandra.dv@toradex.com; linux-serial@vger.kernel.org; linux- > kernel@vger.kernel.org; dl-linux-imx <linux-imx@nxp.com> > Subject: Re: [PATCH] tty: serial: fsl_lpuart: disable dma rx/tx use flags in > lpuart_dma_shutdown > > On Tue, 20 Sep 2022, Sherry Sun wrote: > > > lpuart_dma_shutdown tears down lpuart dma, but lpuart_flush_buffer can > > still occur which in turn tries to access dma apis if > > lpuart_dma_tx_use flag is true. At this point since dma is torn down, > > these dma apis can abort. Set lpuart_dma_tx_use and the corresponding > > rx flag lpuart_dma_rx_use to false in lpuart_dma_shutdown so that dmas > > are not accessed after they are relinquished. > > > > Otherwise, when try to kill btattach, kernel may panic. This patch may > > fix this issue. > > root@imx8ulpevk:~# btattach -B /dev/ttyLP2 -S 115200 > > ^C[ 90.182296] Internal error: synchronous external abort: 96000210 [#1] > PREEMPT SMP > > [ 90.189806] Modules linked in: moal(O) mlan(O) > > [ 90.194258] CPU: 0 PID: 503 Comm: btattach Tainted: G O > 5.15.32-06136-g34eecdf2f9e4 #37 > > [ 90.203554] Hardware name: NXP i.MX8ULP 9X9 EVK (DT) > > [ 90.208513] pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS > BTYPE=--) > > [ 90.215470] pc : fsl_edma3_disable_request+0x8/0x60 > > [ 90.220358] lr : fsl_edma3_terminate_all+0x34/0x20c > > [ 90.225237] sp : ffff800013f0bac0 > > [ 90.228548] x29: ffff800013f0bac0 x28: 0000000000000001 x27: > ffff000008404800 > > [ 90.235681] x26: ffff000008404960 x25: ffff000008404a08 x24: > ffff000008404a00 > > [ 90.242813] x23: ffff000008404a60 x22: 0000000000000002 x21: > 0000000000000000 > > [ 90.249946] x20: ffff800013f0baf8 x19: ffff00000559c800 x18: > 0000000000000000 > > [ 90.257078] x17: 0000000000000000 x16: 0000000000000000 x15: > 0000000000000000 > > [ 90.264211] x14: 0000000000000003 x13: 0000000000000000 x12: > 0000000000000040 > > [ 90.271344] x11: ffff00000600c248 x10: ffff800013f0bb10 x9 : > ffff000057bcb090 > > [ 90.278477] x8 : fffffc0000241a08 x7 : ffff00000534ee00 x6 : > ffff000008404804 > > [ 90.285609] x5 : 0000000000000000 x4 : 0000000000000000 x3 : > ffff0000055b3480 > > [ 90.292742] x2 : ffff8000135c0000 x1 : ffff00000534ee00 x0 : > ffff00000559c800 > > [ 90.299876] Call trace: > > [ 90.302321] fsl_edma3_disable_request+0x8/0x60 > > [ 90.306851] lpuart_flush_buffer+0x40/0x160 > > [ 90.311037] uart_flush_buffer+0x88/0x120 > > [ 90.315050] tty_driver_flush_buffer+0x20/0x30 > > [ 90.319496] hci_uart_flush+0x44/0x90 > > [ 90.323162] +0x34/0x12c > > [ 90.327253] tty_ldisc_close+0x38/0x70 > > [ 90.331005] tty_ldisc_release+0xa8/0x190 > > [ 90.335018] tty_release_struct+0x24/0x8c > > [ 90.339022] tty_release+0x3ec/0x4c0 > > [ 90.342593] __fput+0x70/0x234 > > [ 90.345652] ____fput+0x14/0x20 > > [ 90.348790] task_work_run+0x84/0x17c > > [ 90.352455] do_exit+0x310/0x96c > > [ 90.355688] do_group_exit+0x3c/0xa0 > > [ 90.359259] __arm64_sys_exit_group+0x1c/0x20 > > [ 90.363609] invoke_syscall+0x48/0x114 > > [ 90.367362] el0_svc_common.constprop.0+0xd4/0xfc > > [ 90.372068] do_el0_svc+0x2c/0x94 > > [ 90.375379] el0_svc+0x28/0x80 > > [ 90.378438] el0t_64_sync_handler+0xa8/0x130 > > [ 90.382711] el0t_64_sync+0x1a0/0x1a4 > > [ 90.386376] Code: 17ffffda d503201f d503233f f9409802 (b9400041) > > [ 90.392467] ---[ end trace 2f60524b4a43f1f6 ]--- > > [ 90.397073] note: btattach[503] exited with preempt_count 1 > > [ 90.402636] Fixing recursive fault but reboot is needed! > > > > Fixes: 6250cc30c4c4 ("tty: serial: fsl_lpuart: Use scatter/gather DMA > > for Tx") > > Signed-off-by: Thara Gopinath <tgopinath@microsoft.com> > > Signed-off-by: Sherry Sun <sherry.sun@nxp.com> > > --- > > drivers/tty/serial/fsl_lpuart.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/drivers/tty/serial/fsl_lpuart.c > > b/drivers/tty/serial/fsl_lpuart.c index f21915015d67..064bd1f33c21 > > 100644 > > --- a/drivers/tty/serial/fsl_lpuart.c > > +++ b/drivers/tty/serial/fsl_lpuart.c > > @@ -1771,6 +1771,7 @@ static void lpuart_dma_shutdown(struct > lpuart_port *sport) > > if (sport->lpuart_dma_rx_use) { > > del_timer_sync(&sport->lpuart_timer); > > lpuart_dma_rx_free(&sport->port); > > + sport->lpuart_dma_rx_use = false; > > } > > > > if (sport->lpuart_dma_tx_use) { > > @@ -1779,6 +1780,7 @@ static void lpuart_dma_shutdown(struct > lpuart_port *sport) > > sport->dma_tx_in_progress = false; > > dmaengine_terminate_all(sport->dma_tx_chan); > > } > > + sport->lpuart_dma_tx_use = false; > > } > > > > if (sport->dma_tx_chan) > > Isn't it still racy because lpuart_dma_shutdown() is called outside of port's > lock? Hi Ilpo, do you think add the following changes should work for this? diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index 064bd1f33c21..b3c53935fbc8 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -1768,10 +1768,14 @@ static int lpuart32_startup(struct uart_port *port) static void lpuart_dma_shutdown(struct lpuart_port *sport) { + unsigned long flags; + if (sport->lpuart_dma_rx_use) { del_timer_sync(&sport->lpuart_timer); lpuart_dma_rx_free(&sport->port); + spin_lock_irqsave(&sport->port.lock, flags); sport->lpuart_dma_rx_use = false; + spin_unlock_irqrestore(&sport->port.lock, flags); } if (sport->lpuart_dma_tx_use) { @@ -1780,7 +1784,9 @@ static void lpuart_dma_shutdown(struct lpuart_port *sport) sport->dma_tx_in_progress = false; dmaengine_terminate_all(sport->dma_tx_chan); } + spin_lock_irqsave(&sport->port.lock, flags); sport->lpuart_dma_tx_use = false; + spin_unlock_irqrestore(&sport->port.lock, flags); } Best Regards Sherry ^ permalink raw reply related [flat|nested] 6+ messages in thread
* RE: [PATCH] tty: serial: fsl_lpuart: disable dma rx/tx use flags in lpuart_dma_shutdown 2022-09-20 14:04 ` Sherry Sun @ 2022-09-21 8:43 ` Ilpo Järvinen 2022-09-21 10:36 ` Sherry Sun 0 siblings, 1 reply; 6+ messages in thread From: Ilpo Järvinen @ 2022-09-21 8:43 UTC (permalink / raw) To: Sherry Sun Cc: gregkh@linuxfoundation.org, jirislaby@kernel.org, bhuvanchandra.dv@toradex.com, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, dl-linux-imx [-- Attachment #1: Type: text/plain, Size: 6654 bytes --] On Tue, 20 Sep 2022, Sherry Sun wrote: > > > > -----Original Message----- > > From: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> > > Sent: 2022年9月20日 20:26 > > To: Sherry Sun <sherry.sun@nxp.com> > > Cc: gregkh@linuxfoundation.org; jirislaby@kernel.org; > > bhuvanchandra.dv@toradex.com; linux-serial@vger.kernel.org; linux- > > kernel@vger.kernel.org; dl-linux-imx <linux-imx@nxp.com> > > Subject: Re: [PATCH] tty: serial: fsl_lpuart: disable dma rx/tx use flags in > > lpuart_dma_shutdown > > > > On Tue, 20 Sep 2022, Sherry Sun wrote: > > > > > lpuart_dma_shutdown tears down lpuart dma, but lpuart_flush_buffer can > > > still occur which in turn tries to access dma apis if > > > lpuart_dma_tx_use flag is true. At this point since dma is torn down, > > > these dma apis can abort. Set lpuart_dma_tx_use and the corresponding > > > rx flag lpuart_dma_rx_use to false in lpuart_dma_shutdown so that dmas > > > are not accessed after they are relinquished. > > > > > > Otherwise, when try to kill btattach, kernel may panic. This patch may > > > fix this issue. > > > root@imx8ulpevk:~# btattach -B /dev/ttyLP2 -S 115200 > > > ^C[ 90.182296] Internal error: synchronous external abort: 96000210 [#1] > > PREEMPT SMP > > > [ 90.189806] Modules linked in: moal(O) mlan(O) > > > [ 90.194258] CPU: 0 PID: 503 Comm: btattach Tainted: G O > > 5.15.32-06136-g34eecdf2f9e4 #37 > > > [ 90.203554] Hardware name: NXP i.MX8ULP 9X9 EVK (DT) > > > [ 90.208513] pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS > > BTYPE=--) > > > [ 90.215470] pc : fsl_edma3_disable_request+0x8/0x60 > > > [ 90.220358] lr : fsl_edma3_terminate_all+0x34/0x20c > > > [ 90.225237] sp : ffff800013f0bac0 > > > [ 90.228548] x29: ffff800013f0bac0 x28: 0000000000000001 x27: > > ffff000008404800 > > > [ 90.235681] x26: ffff000008404960 x25: ffff000008404a08 x24: > > ffff000008404a00 > > > [ 90.242813] x23: ffff000008404a60 x22: 0000000000000002 x21: > > 0000000000000000 > > > [ 90.249946] x20: ffff800013f0baf8 x19: ffff00000559c800 x18: > > 0000000000000000 > > > [ 90.257078] x17: 0000000000000000 x16: 0000000000000000 x15: > > 0000000000000000 > > > [ 90.264211] x14: 0000000000000003 x13: 0000000000000000 x12: > > 0000000000000040 > > > [ 90.271344] x11: ffff00000600c248 x10: ffff800013f0bb10 x9 : > > ffff000057bcb090 > > > [ 90.278477] x8 : fffffc0000241a08 x7 : ffff00000534ee00 x6 : > > ffff000008404804 > > > [ 90.285609] x5 : 0000000000000000 x4 : 0000000000000000 x3 : > > ffff0000055b3480 > > > [ 90.292742] x2 : ffff8000135c0000 x1 : ffff00000534ee00 x0 : > > ffff00000559c800 > > > [ 90.299876] Call trace: > > > [ 90.302321] fsl_edma3_disable_request+0x8/0x60 > > > [ 90.306851] lpuart_flush_buffer+0x40/0x160 > > > [ 90.311037] uart_flush_buffer+0x88/0x120 > > > [ 90.315050] tty_driver_flush_buffer+0x20/0x30 > > > [ 90.319496] hci_uart_flush+0x44/0x90 > > > [ 90.323162] +0x34/0x12c > > > [ 90.327253] tty_ldisc_close+0x38/0x70 > > > [ 90.331005] tty_ldisc_release+0xa8/0x190 > > > [ 90.335018] tty_release_struct+0x24/0x8c > > > [ 90.339022] tty_release+0x3ec/0x4c0 > > > [ 90.342593] __fput+0x70/0x234 > > > [ 90.345652] ____fput+0x14/0x20 > > > [ 90.348790] task_work_run+0x84/0x17c > > > [ 90.352455] do_exit+0x310/0x96c > > > [ 90.355688] do_group_exit+0x3c/0xa0 > > > [ 90.359259] __arm64_sys_exit_group+0x1c/0x20 > > > [ 90.363609] invoke_syscall+0x48/0x114 > > > [ 90.367362] el0_svc_common.constprop.0+0xd4/0xfc > > > [ 90.372068] do_el0_svc+0x2c/0x94 > > > [ 90.375379] el0_svc+0x28/0x80 > > > [ 90.378438] el0t_64_sync_handler+0xa8/0x130 > > > [ 90.382711] el0t_64_sync+0x1a0/0x1a4 > > > [ 90.386376] Code: 17ffffda d503201f d503233f f9409802 (b9400041) > > > [ 90.392467] ---[ end trace 2f60524b4a43f1f6 ]--- > > > [ 90.397073] note: btattach[503] exited with preempt_count 1 > > > [ 90.402636] Fixing recursive fault but reboot is needed! > > > > > > Fixes: 6250cc30c4c4 ("tty: serial: fsl_lpuart: Use scatter/gather DMA > > > for Tx") > > > Signed-off-by: Thara Gopinath <tgopinath@microsoft.com> > > > Signed-off-by: Sherry Sun <sherry.sun@nxp.com> > > > --- > > > drivers/tty/serial/fsl_lpuart.c | 2 ++ > > > 1 file changed, 2 insertions(+) > > > > > > diff --git a/drivers/tty/serial/fsl_lpuart.c > > > b/drivers/tty/serial/fsl_lpuart.c index f21915015d67..064bd1f33c21 > > > 100644 > > > --- a/drivers/tty/serial/fsl_lpuart.c > > > +++ b/drivers/tty/serial/fsl_lpuart.c > > > @@ -1771,6 +1771,7 @@ static void lpuart_dma_shutdown(struct > > lpuart_port *sport) > > > if (sport->lpuart_dma_rx_use) { > > > del_timer_sync(&sport->lpuart_timer); > > > lpuart_dma_rx_free(&sport->port); > > > + sport->lpuart_dma_rx_use = false; > > > } > > > > > > if (sport->lpuart_dma_tx_use) { > > > @@ -1779,6 +1780,7 @@ static void lpuart_dma_shutdown(struct > > lpuart_port *sport) > > > sport->dma_tx_in_progress = false; > > > dmaengine_terminate_all(sport->dma_tx_chan); > > > } > > > + sport->lpuart_dma_tx_use = false; > > > } > > > > > > if (sport->dma_tx_chan) > > > > Isn't it still racy because lpuart_dma_shutdown() is called outside of port's > > lock? > > Hi Ilpo, do you think add the following changes should work for this? > > diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c > index 064bd1f33c21..b3c53935fbc8 100644 > --- a/drivers/tty/serial/fsl_lpuart.c > +++ b/drivers/tty/serial/fsl_lpuart.c > @@ -1768,10 +1768,14 @@ static int lpuart32_startup(struct uart_port *port) > > static void lpuart_dma_shutdown(struct lpuart_port *sport) > { > + unsigned long flags; > + > if (sport->lpuart_dma_rx_use) { > del_timer_sync(&sport->lpuart_timer); > lpuart_dma_rx_free(&sport->port); > + spin_lock_irqsave(&sport->port.lock, flags); > sport->lpuart_dma_rx_use = false; > + spin_unlock_irqrestore(&sport->port.lock, flags); > } > > if (sport->lpuart_dma_tx_use) { > @@ -1780,7 +1784,9 @@ static void lpuart_dma_shutdown(struct lpuart_port *sport) > sport->dma_tx_in_progress = false; > dmaengine_terminate_all(sport->dma_tx_chan); > } > + spin_lock_irqsave(&sport->port.lock, flags); > sport->lpuart_dma_tx_use = false; > + spin_unlock_irqrestore(&sport->port.lock, flags); > } After reading a bit more, I think the original patch is likely fine since shutdown doesn't seem to be racing with flush_buffer. -- i. ^ permalink raw reply [flat|nested] 6+ messages in thread
* RE: [PATCH] tty: serial: fsl_lpuart: disable dma rx/tx use flags in lpuart_dma_shutdown 2022-09-21 8:43 ` Ilpo Järvinen @ 2022-09-21 10:36 ` Sherry Sun 0 siblings, 0 replies; 6+ messages in thread From: Sherry Sun @ 2022-09-21 10:36 UTC (permalink / raw) To: Ilpo Järvinen Cc: gregkh@linuxfoundation.org, jirislaby@kernel.org, bhuvanchandra.dv@toradex.com, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, dl-linux-imx > > > > > > On Tue, 20 Sep 2022, Sherry Sun wrote: > > > > > > > lpuart_dma_shutdown tears down lpuart dma, but lpuart_flush_buffer > > > > can still occur which in turn tries to access dma apis if > > > > lpuart_dma_tx_use flag is true. At this point since dma is torn > > > > down, these dma apis can abort. Set lpuart_dma_tx_use and the > > > > corresponding rx flag lpuart_dma_rx_use to false in > > > > lpuart_dma_shutdown so that dmas are not accessed after they are > relinquished. > > > > > > > > Otherwise, when try to kill btattach, kernel may panic. This patch > > > > may fix this issue. > > > > root@imx8ulpevk:~# btattach -B /dev/ttyLP2 -S 115200 > > > > ^C[ 90.182296] Internal error: synchronous external abort: 96000210 > [#1] > > > PREEMPT SMP > > > > [ 90.189806] Modules linked in: moal(O) mlan(O) > > > > [ 90.194258] CPU: 0 PID: 503 Comm: btattach Tainted: G O > > > 5.15.32-06136-g34eecdf2f9e4 #37 > > > > [ 90.203554] Hardware name: NXP i.MX8ULP 9X9 EVK (DT) > > > > [ 90.208513] pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS > > > BTYPE=--) > > > > [ 90.215470] pc : fsl_edma3_disable_request+0x8/0x60 > > > > [ 90.220358] lr : fsl_edma3_terminate_all+0x34/0x20c > > > > [ 90.225237] sp : ffff800013f0bac0 > > > > [ 90.228548] x29: ffff800013f0bac0 x28: 0000000000000001 x27: > > > ffff000008404800 > > > > [ 90.235681] x26: ffff000008404960 x25: ffff000008404a08 x24: > > > ffff000008404a00 > > > > [ 90.242813] x23: ffff000008404a60 x22: 0000000000000002 x21: > > > 0000000000000000 > > > > [ 90.249946] x20: ffff800013f0baf8 x19: ffff00000559c800 x18: > > > 0000000000000000 > > > > [ 90.257078] x17: 0000000000000000 x16: 0000000000000000 x15: > > > 0000000000000000 > > > > [ 90.264211] x14: 0000000000000003 x13: 0000000000000000 x12: > > > 0000000000000040 > > > > [ 90.271344] x11: ffff00000600c248 x10: ffff800013f0bb10 x9 : > > > ffff000057bcb090 > > > > [ 90.278477] x8 : fffffc0000241a08 x7 : ffff00000534ee00 x6 : > > > ffff000008404804 > > > > [ 90.285609] x5 : 0000000000000000 x4 : 0000000000000000 x3 : > > > ffff0000055b3480 > > > > [ 90.292742] x2 : ffff8000135c0000 x1 : ffff00000534ee00 x0 : > > > ffff00000559c800 > > > > [ 90.299876] Call trace: > > > > [ 90.302321] fsl_edma3_disable_request+0x8/0x60 > > > > [ 90.306851] lpuart_flush_buffer+0x40/0x160 > > > > [ 90.311037] uart_flush_buffer+0x88/0x120 > > > > [ 90.315050] tty_driver_flush_buffer+0x20/0x30 > > > > [ 90.319496] hci_uart_flush+0x44/0x90 > > > > [ 90.323162] +0x34/0x12c > > > > [ 90.327253] tty_ldisc_close+0x38/0x70 > > > > [ 90.331005] tty_ldisc_release+0xa8/0x190 > > > > [ 90.335018] tty_release_struct+0x24/0x8c > > > > [ 90.339022] tty_release+0x3ec/0x4c0 > > > > [ 90.342593] __fput+0x70/0x234 > > > > [ 90.345652] ____fput+0x14/0x20 > > > > [ 90.348790] task_work_run+0x84/0x17c > > > > [ 90.352455] do_exit+0x310/0x96c > > > > [ 90.355688] do_group_exit+0x3c/0xa0 > > > > [ 90.359259] __arm64_sys_exit_group+0x1c/0x20 > > > > [ 90.363609] invoke_syscall+0x48/0x114 > > > > [ 90.367362] el0_svc_common.constprop.0+0xd4/0xfc > > > > [ 90.372068] do_el0_svc+0x2c/0x94 > > > > [ 90.375379] el0_svc+0x28/0x80 > > > > [ 90.378438] el0t_64_sync_handler+0xa8/0x130 > > > > [ 90.382711] el0t_64_sync+0x1a0/0x1a4 > > > > [ 90.386376] Code: 17ffffda d503201f d503233f f9409802 (b9400041) > > > > [ 90.392467] ---[ end trace 2f60524b4a43f1f6 ]--- > > > > [ 90.397073] note: btattach[503] exited with preempt_count 1 > > > > [ 90.402636] Fixing recursive fault but reboot is needed! > > > > > > > > Fixes: 6250cc30c4c4 ("tty: serial: fsl_lpuart: Use scatter/gather > > > > DMA for Tx") > > > > Signed-off-by: Thara Gopinath <tgopinath@microsoft.com> > > > > Signed-off-by: Sherry Sun <sherry.sun@nxp.com> > > > > --- > > > > drivers/tty/serial/fsl_lpuart.c | 2 ++ > > > > 1 file changed, 2 insertions(+) > > > > > > > > diff --git a/drivers/tty/serial/fsl_lpuart.c > > > > b/drivers/tty/serial/fsl_lpuart.c index f21915015d67..064bd1f33c21 > > > > 100644 > > > > --- a/drivers/tty/serial/fsl_lpuart.c > > > > +++ b/drivers/tty/serial/fsl_lpuart.c > > > > @@ -1771,6 +1771,7 @@ static void lpuart_dma_shutdown(struct > > > lpuart_port *sport) > > > > if (sport->lpuart_dma_rx_use) { > > > > del_timer_sync(&sport->lpuart_timer); > > > > lpuart_dma_rx_free(&sport->port); > > > > + sport->lpuart_dma_rx_use = false; > > > > } > > > > > > > > if (sport->lpuart_dma_tx_use) { > > > > @@ -1779,6 +1780,7 @@ static void lpuart_dma_shutdown(struct > > > lpuart_port *sport) > > > > sport->dma_tx_in_progress = false; > > > > dmaengine_terminate_all(sport->dma_tx_chan); > > > > } > > > > + sport->lpuart_dma_tx_use = false; > > > > } > > > > > > > > if (sport->dma_tx_chan) > > > > > > Isn't it still racy because lpuart_dma_shutdown() is called outside > > > of port's lock? > > > > Hi Ilpo, do you think add the following changes should work for this? > > > > diff --git a/drivers/tty/serial/fsl_lpuart.c > > b/drivers/tty/serial/fsl_lpuart.c index 064bd1f33c21..b3c53935fbc8 > > 100644 > > --- a/drivers/tty/serial/fsl_lpuart.c > > +++ b/drivers/tty/serial/fsl_lpuart.c > > @@ -1768,10 +1768,14 @@ static int lpuart32_startup(struct uart_port > > *port) > > > > static void lpuart_dma_shutdown(struct lpuart_port *sport) { > > + unsigned long flags; > > + > > if (sport->lpuart_dma_rx_use) { > > del_timer_sync(&sport->lpuart_timer); > > lpuart_dma_rx_free(&sport->port); > > + spin_lock_irqsave(&sport->port.lock, flags); > > sport->lpuart_dma_rx_use = false; > > + spin_unlock_irqrestore(&sport->port.lock, flags); > > } > > > > if (sport->lpuart_dma_tx_use) { @@ -1780,7 +1784,9 @@ static > > void lpuart_dma_shutdown(struct lpuart_port *sport) > > sport->dma_tx_in_progress = false; > > dmaengine_terminate_all(sport->dma_tx_chan); > > } > > + spin_lock_irqsave(&sport->port.lock, flags); > > sport->lpuart_dma_tx_use = false; > > + spin_unlock_irqrestore(&sport->port.lock, flags); > > } > > After reading a bit more, I think the original patch is likely fine since > shutdown doesn't seem to be racing with flush_buffer. > Good, thanks for the updates. Best Regards Sherry ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] tty: serial: fsl_lpuart: disable dma rx/tx use flags in lpuart_dma_shutdown 2022-09-20 11:17 [PATCH] tty: serial: fsl_lpuart: disable dma rx/tx use flags in lpuart_dma_shutdown Sherry Sun 2022-09-20 12:25 ` Ilpo Järvinen @ 2022-09-21 8:45 ` Ilpo Järvinen 1 sibling, 0 replies; 6+ messages in thread From: Ilpo Järvinen @ 2022-09-21 8:45 UTC (permalink / raw) To: Sherry Sun Cc: Greg Kroah-Hartman, Jiri Slaby, bhuvanchandra.dv, linux-serial, LKML, linux-imx [-- Attachment #1: Type: text/plain, Size: 4295 bytes --] On Tue, 20 Sep 2022, Sherry Sun wrote: > lpuart_dma_shutdown tears down lpuart dma, but lpuart_flush_buffer can > still occur which in turn tries to access dma apis if lpuart_dma_tx_use > flag is true. At this point since dma is torn down, these dma apis can > abort. Set lpuart_dma_tx_use and the corresponding rx flag > lpuart_dma_rx_use to false in lpuart_dma_shutdown so that dmas are not > accessed after they are relinquished. > > Otherwise, when try to kill btattach, kernel may panic. This patch may > fix this issue. > root@imx8ulpevk:~# btattach -B /dev/ttyLP2 -S 115200 > ^C[ 90.182296] Internal error: synchronous external abort: 96000210 [#1] PREEMPT SMP > [ 90.189806] Modules linked in: moal(O) mlan(O) > [ 90.194258] CPU: 0 PID: 503 Comm: btattach Tainted: G O 5.15.32-06136-g34eecdf2f9e4 #37 > [ 90.203554] Hardware name: NXP i.MX8ULP 9X9 EVK (DT) > [ 90.208513] pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--) > [ 90.215470] pc : fsl_edma3_disable_request+0x8/0x60 > [ 90.220358] lr : fsl_edma3_terminate_all+0x34/0x20c > [ 90.225237] sp : ffff800013f0bac0 > [ 90.228548] x29: ffff800013f0bac0 x28: 0000000000000001 x27: ffff000008404800 > [ 90.235681] x26: ffff000008404960 x25: ffff000008404a08 x24: ffff000008404a00 > [ 90.242813] x23: ffff000008404a60 x22: 0000000000000002 x21: 0000000000000000 > [ 90.249946] x20: ffff800013f0baf8 x19: ffff00000559c800 x18: 0000000000000000 > [ 90.257078] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000 > [ 90.264211] x14: 0000000000000003 x13: 0000000000000000 x12: 0000000000000040 > [ 90.271344] x11: ffff00000600c248 x10: ffff800013f0bb10 x9 : ffff000057bcb090 > [ 90.278477] x8 : fffffc0000241a08 x7 : ffff00000534ee00 x6 : ffff000008404804 > [ 90.285609] x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff0000055b3480 > [ 90.292742] x2 : ffff8000135c0000 x1 : ffff00000534ee00 x0 : ffff00000559c800 > [ 90.299876] Call trace: > [ 90.302321] fsl_edma3_disable_request+0x8/0x60 > [ 90.306851] lpuart_flush_buffer+0x40/0x160 > [ 90.311037] uart_flush_buffer+0x88/0x120 > [ 90.315050] tty_driver_flush_buffer+0x20/0x30 > [ 90.319496] hci_uart_flush+0x44/0x90 > [ 90.323162] +0x34/0x12c > [ 90.327253] tty_ldisc_close+0x38/0x70 > [ 90.331005] tty_ldisc_release+0xa8/0x190 > [ 90.335018] tty_release_struct+0x24/0x8c > [ 90.339022] tty_release+0x3ec/0x4c0 > [ 90.342593] __fput+0x70/0x234 > [ 90.345652] ____fput+0x14/0x20 > [ 90.348790] task_work_run+0x84/0x17c > [ 90.352455] do_exit+0x310/0x96c > [ 90.355688] do_group_exit+0x3c/0xa0 > [ 90.359259] __arm64_sys_exit_group+0x1c/0x20 > [ 90.363609] invoke_syscall+0x48/0x114 > [ 90.367362] el0_svc_common.constprop.0+0xd4/0xfc > [ 90.372068] do_el0_svc+0x2c/0x94 > [ 90.375379] el0_svc+0x28/0x80 > [ 90.378438] el0t_64_sync_handler+0xa8/0x130 > [ 90.382711] el0t_64_sync+0x1a0/0x1a4 > [ 90.386376] Code: 17ffffda d503201f d503233f f9409802 (b9400041) > [ 90.392467] ---[ end trace 2f60524b4a43f1f6 ]--- > [ 90.397073] note: btattach[503] exited with preempt_count 1 > [ 90.402636] Fixing recursive fault but reboot is needed! > > Fixes: 6250cc30c4c4 ("tty: serial: fsl_lpuart: Use scatter/gather DMA for Tx") > Signed-off-by: Thara Gopinath <tgopinath@microsoft.com> > Signed-off-by: Sherry Sun <sherry.sun@nxp.com> > --- > drivers/tty/serial/fsl_lpuart.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c > index f21915015d67..064bd1f33c21 100644 > --- a/drivers/tty/serial/fsl_lpuart.c > +++ b/drivers/tty/serial/fsl_lpuart.c > @@ -1771,6 +1771,7 @@ static void lpuart_dma_shutdown(struct lpuart_port *sport) > if (sport->lpuart_dma_rx_use) { > del_timer_sync(&sport->lpuart_timer); > lpuart_dma_rx_free(&sport->port); > + sport->lpuart_dma_rx_use = false; > } > > if (sport->lpuart_dma_tx_use) { > @@ -1779,6 +1780,7 @@ static void lpuart_dma_shutdown(struct lpuart_port *sport) > sport->dma_tx_in_progress = false; > dmaengine_terminate_all(sport->dma_tx_chan); > } > + sport->lpuart_dma_tx_use = false; > } > > if (sport->dma_tx_chan) Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> -- i. ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2022-09-21 10:36 UTC | newest] Thread overview: 6+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2022-09-20 11:17 [PATCH] tty: serial: fsl_lpuart: disable dma rx/tx use flags in lpuart_dma_shutdown Sherry Sun 2022-09-20 12:25 ` Ilpo Järvinen 2022-09-20 14:04 ` Sherry Sun 2022-09-21 8:43 ` Ilpo Järvinen 2022-09-21 10:36 ` Sherry Sun 2022-09-21 8:45 ` Ilpo Järvinen
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