linux/drivers/tty/serial/serial_core.c

2816 lines
70 KiB

TTY: serial_core: Fix crash if DCD drop during suspend This crash was showing up 100% of the time on Tegra CPUs when an agetty was running on the serial port and the console was not running on the serial port. The reason the Tegra saw it so reliably is that the Tegra CPU internally ties DTR to DCD/DSR. That means when we dropped DTR during suspend we would get always get an immediate DCD drop. The specific order of operations that were running: * uart_suspend_port() would be called to put the uart in suspend mode * we'd drop DTR (ops->set_mctrl(uport, 0)). * the DTR drop would be looped back in the CPU to be a DCD drop. * the DCD drop would look to the serial driver as a hangup * the hangup would call uart_shutdown() * ... suspend / resume happens ... * uart_resume_port() would be called and run the code in the (port->flags & ASYNC_SUSPENDED) block, which would startup the port (and enable tx again). * Since the UART would be available for tx, we'd immediately get an interrupt, eventually calling transmit_chars() * The transmit_chars() function would crash. The first crash would be a dereference of a NULL tty member, but since the port has been shutdown that was just a symptom. I have proposed a patch that would fix the Tegra CPUs here (see https://lkml.org/lkml/2011/10/11/444 - tty/serial: Prevent drop of DCD on suspend for Tegra UARTs). However, even with that fix it is still possible for systems that have an externally visible DCD line to see a crash if the DCD drops at just the right time during suspend: thus this patch is still useful. Signed-off-by: Doug Anderson <dianders@chromium.org> Acked-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-10-19 11:52:01 -07:00
TTY: serial_core: Fix crash if DCD drop during suspend This crash was showing up 100% of the time on Tegra CPUs when an agetty was running on the serial port and the console was not running on the serial port. The reason the Tegra saw it so reliably is that the Tegra CPU internally ties DTR to DCD/DSR. That means when we dropped DTR during suspend we would get always get an immediate DCD drop. The specific order of operations that were running: * uart_suspend_port() would be called to put the uart in suspend mode * we'd drop DTR (ops->set_mctrl(uport, 0)). * the DTR drop would be looped back in the CPU to be a DCD drop. * the DCD drop would look to the serial driver as a hangup * the hangup would call uart_shutdown() * ... suspend / resume happens ... * uart_resume_port() would be called and run the code in the (port->flags & ASYNC_SUSPENDED) block, which would startup the port (and enable tx again). * Since the UART would be available for tx, we'd immediately get an interrupt, eventually calling transmit_chars() * The transmit_chars() function would crash. The first crash would be a dereference of a NULL tty member, but since the port has been shutdown that was just a symptom. I have proposed a patch that would fix the Tegra CPUs here (see https://lkml.org/lkml/2011/10/11/444 - tty/serial: Prevent drop of DCD on suspend for Tegra UARTs). However, even with that fix it is still possible for systems that have an externally visible DCD line to see a crash if the DCD drops at just the right time during suspend: thus this patch is still useful. Signed-off-by: Doug Anderson <dianders@chromium.org> Acked-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-10-19 11:52:01 -07:00
TTY: serial: Move mutex_unlock in uart_close function When mutex_lock is not called, mutex_unlock is sometimes called. This deletes unnecessary goto and makes modifications so that mutex_unlock is called. [ 8.304000] WARNING: at kernel/muex-debug.c:78 [ 8.304000] Modules linked in: [ 8.304000] [ 8.304000] Pid : 114, Comm: modprobe [ 8.304000] CPU : 0 Not tainted (3.1.0-rc3-next-20110826 #810) [ 8.304000] [ 8.304000] PC is at debug_mutex_unlock+0xf4/0x120 [ 8.304000] PR is at debug_mutex_unlock+0xe6/0x120 [ 8.304000] PC : 80051114 SP : 9f02de58 SR : 400081f1 TEA : 295cf4f2 [ 8.304000] R0 : 00000001 R1 : 00000000 R2 : 0000000f R3 : 00000000 [ 8.304000] R4 : 9fc63158 R5 : 00000000 R6 : 00000001 R7 : 9fe1de78 [ 8.304000] R8 : 805c6b2c R9 : 80003920 R10 : 00000000 R11 : 805c6b2c [ 8.304000] R12 : 80425ca0 R13 : 00000000 R14 : 9f02de58 [ 8.304000] MACH: 00000003 MACL: 00000000 GBR : 296e1678 PR : 80051106 [ 8.304000] [ 8.304000] Call trace: [ 8.304000] [<804236c6>] __mutex_unlock_slowpath+0x46/0x120 [ 8.304000] [<804237aa>] mutex_unlock+0xa/0x20 [ 8.304000] [<80240ed6>] uart_close+0x76/0x2c0 [ 8.304000] [<80223b98>] tty_release+0xf8/0x5c0 [ 8.304000] [<800a93a6>] lookup_object+0x26/0xa0 [ 8.304000] [<80063f6a>] call_rcu+0x8a/0xc0 [ 8.304000] [<800a944a>] put_object+0x2a/0x60 [ 8.304000] [<80003920>] arch_local_irq_restore+0x0/0x40 [ 8.304000] [<800af320>] fput+0x180/0x2c0 [ 8.304000] [<800af248>] fput+0xa8/0x2c0 [ 8.304000] [<800ab1a8>] filp_close+0x48/0xc0 [ 8.304000] [<800ab29a>] sys_close+0x7a/0x100 [ 8.304000] [<8000825a>] syscall_call+0xc/0x10 [ 8.304000] [<800ab220>] sys_close+0x0/0x100 [ 8.304000] [ 8.304000] Code: [ 8.304000] 8005110e: mov.l @r1, r1 [ 8.304000] 80051110: tst r1, r1 [ 8.304000] 80051112: bf 80051116 [ 8.304000] ->80051114: trapa #62 [ 8.304000] 80051116: mov.l @r8, r1 [ 8.304000] 80051118: tst r1, r1 [ 8.304000] 8005111a: bt.s 8005104c [ 8.304000] 8005111c: mov #0, r1 [ 8.304000] 8005111e: bra 80051056 [ 8.304000] [ 8.304000] ---[ end trace e8f8e04c313f429b ]--- Signed-off-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com> Signed-off-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-08-29 15:43:36 +09:00
serial-core: reset the console speed on resume On some platforms, we need to restore the console speed on resume even it was not suspended (no_console_suspend), and on others we don't have to do that. So don't care about the "console_suspend_enabled" and unconditionally reset the console speed if it is a console. This is actually a redo of ba15ab0 (Set proper console speed on resume if console suspend is disabled) from Deepak Saxena. I also tried to investigate more to find out if this change will break others, here is what I've found out: commit 891b9dd10764352926e1e107756aa229dfa2c210 Author: Jason Wang <jason77.wang@gmail.com> serial-core: restore termios settings when resume console ports commit ca2e71aa8cfb0056ce720f3fd53f59f5fac4a3e1 Author: Jason Wang <jason77.wang@gmail.com> serial-core: skip call set_termios/console_start when no_console_suspend commit 4547be7809a3b775ce750ec7f8b5748954741523 Author: Stanislav Brabec <sbrabec@suse.cz> serial-core: resume serial hardware with no_console_suspend commit ba15ab0e8de0d4439a91342ad52d55ca9e313f3d Author: Deepak Saxena <dsaxena@laptop.org> Set proper console speed on resume if console suspend is disabled from ba15ab0, we learned that, even if the console suspend is disabled (when no_console_suspend is set), we may still need to "reset the port to the state it was in before we suspended." Then with 4547be7, this piece of code is removed. And then Jason Wang added that back in ca2e71a and 891b9dd, to fix some breakage on OMAP3EVM platform. From ca2e71a we learned that the "set_termios" things is actually needed by both console is suspended and not suspended. That's why I removed the console_suspended_enabled condition, and only call console_start() when we actually suspeneded it. I also noticed in this thread: http://marc.info/?t=129079257100004&r=1&w=2, which talked about on some platforms, UART HW will be cut power whether or not we set no_console_suspend, and then on resume it does not work quite well. I have a similar HW, and this patch fixed this issue, don't know if this patch also works on their platforms. [Update: Stanislav tested this patch on Zaurus and reported it improves the situation. Thanks.] CC: Greg KH <greg@kroah.com> CC: Deepak Saxena <dsaxena@laptop.org> CC: Jason Wang <jason77.wang@gmail.com> CC: Stanislav Brabec <sbrabec@suse.cz> CC: Daniel Drake <dsd@laptop.org> Signed-off-by: Yin Kangkai <kangkai.yin@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-01-30 11:15:30 +08:00
serial-core: power up uart port early before we do set_termios when resuming The following patch removed uart_change_pm() in uart_resume_port(): commit 5933a161abcb8d83a2c145177f48027c3c0a8995 Author: Yin Kangkai <kangkai.yin@linux.intel.com> serial-core: reset the console speed on resume It will break the pxa serial driver when the system resumes from suspend mode as it will try to set baud rate divider register in set_termios but with clock off. The register value can not be set correctly on some platform if the clock is disabled. The pxa driver will check the value and report the following warning: ------------[ cut here ]------------ WARNING: at drivers/tty/serial/pxa.c:545 serial_pxa_set_termios+0x1dc/0x250() Modules linked in: [<c0281f30>] (unwind_backtrace+0x0/0xf0) from [<c029341c>] (warn_slowpath_common+0x4c/0x64) [<c029341c>] (warn_slowpath_common+0x4c/0x64) from [<c029344c>] (warn_slowpath_null+0x18/0x1c) [<c029344c>] (warn_slowpath_null+0x18/0x1c) from [<c044b1e4>] (serial_pxa_set_termios+0x1dc/0x250) [<c044b1e4>] (serial_pxa_set_termios+0x1dc/0x250) from [<c044a840>] (uart_resume_port+0x128/0x2dc) [<c044a840>] (uart_resume_port+0x128/0x2dc) from [<c044bbe0>] (serial_pxa_resume+0x18/0x24) [<c044bbe0>] (serial_pxa_resume+0x18/0x24) from [<c0454d34>] (platform_pm_resume+0x40/0x4c) [<c0454d34>] (platform_pm_resume+0x40/0x4c) from [<c0457ebc>] (pm_op+0x68/0xb4) [<c0457ebc>] (pm_op+0x68/0xb4) from [<c0458368>] (device_resume+0xb0/0xec) [<c0458368>] (device_resume+0xb0/0xec) from [<c04584c8>] (dpm_resume+0xe0/0x194) [<c04584c8>] (dpm_resume+0xe0/0x194) from [<c0458588>] (dpm_resume_end+0xc/0x18) [<c0458588>] (dpm_resume_end+0xc/0x18) from [<c02c518c>] (suspend_devices_and_enter+0x16c/0x1ac) [<c02c518c>] (suspend_devices_and_enter+0x16c/0x1ac) from [<c02c5278>] (enter_state+0xac/0xdc) [<c02c5278>] (enter_state+0xac/0xdc) from [<c02c48ec>] (state_store+0xa0/0xbc) [<c02c48ec>] (state_store+0xa0/0xbc) from [<c0408f7c>] (kobj_attr_store+0x18/0x1c) [<c0408f7c>] (kobj_attr_store+0x18/0x1c) from [<c034a6a4>] (sysfs_write_file+0x108/0x140) [<c034a6a4>] (sysfs_write_file+0x108/0x140) from [<c02fb798>] (vfs_write+0xac/0x134) [<c02fb798>] (vfs_write+0xac/0x134) from [<c02fb8cc>] (sys_write+0x3c/0x68) [<c02fb8cc>] (sys_write+0x3c/0x68) from [<c027c700>] (ret_fast_syscall+0x0/0x2c) ---[ end trace 88289eceb4675b04 ]--- This patch fix the problem by adding the power on opertion back for uart console when console_suspend_enabled is true. Signed-off-by: Ning Jiang <ning.jiang@marvell.com> Tested-by: Mayank Rana <mrana@codeaurora.org> Cc: stable <stable@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-09-05 16:28:18 +08:00
serial-core: reset the console speed on resume On some platforms, we need to restore the console speed on resume even it was not suspended (no_console_suspend), and on others we don't have to do that. So don't care about the "console_suspend_enabled" and unconditionally reset the console speed if it is a console. This is actually a redo of ba15ab0 (Set proper console speed on resume if console suspend is disabled) from Deepak Saxena. I also tried to investigate more to find out if this change will break others, here is what I've found out: commit 891b9dd10764352926e1e107756aa229dfa2c210 Author: Jason Wang <jason77.wang@gmail.com> serial-core: restore termios settings when resume console ports commit ca2e71aa8cfb0056ce720f3fd53f59f5fac4a3e1 Author: Jason Wang <jason77.wang@gmail.com> serial-core: skip call set_termios/console_start when no_console_suspend commit 4547be7809a3b775ce750ec7f8b5748954741523 Author: Stanislav Brabec <sbrabec@suse.cz> serial-core: resume serial hardware with no_console_suspend commit ba15ab0e8de0d4439a91342ad52d55ca9e313f3d Author: Deepak Saxena <dsaxena@laptop.org> Set proper console speed on resume if console suspend is disabled from ba15ab0, we learned that, even if the console suspend is disabled (when no_console_suspend is set), we may still need to "reset the port to the state it was in before we suspended." Then with 4547be7, this piece of code is removed. And then Jason Wang added that back in ca2e71a and 891b9dd, to fix some breakage on OMAP3EVM platform. From ca2e71a we learned that the "set_termios" things is actually needed by both console is suspended and not suspended. That's why I removed the console_suspended_enabled condition, and only call console_start() when we actually suspeneded it. I also noticed in this thread: http://marc.info/?t=129079257100004&r=1&w=2, which talked about on some platforms, UART HW will be cut power whether or not we set no_console_suspend, and then on resume it does not work quite well. I have a similar HW, and this patch fixed this issue, don't know if this patch also works on their platforms. [Update: Stanislav tested this patch on Zaurus and reported it improves the situation. Thanks.] CC: Greg KH <greg@kroah.com> CC: Deepak Saxena <dsaxena@laptop.org> CC: Jason Wang <jason77.wang@gmail.com> CC: Stanislav Brabec <sbrabec@suse.cz> CC: Daniel Drake <dsd@laptop.org> Signed-off-by: Yin Kangkai <kangkai.yin@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-01-30 11:15:30 +08:00