kernel/drivers/tty/serial/pmac_zilog.c, branch linux-6.9.y

serial/pmac_zilog: Remove flawed mitigation for rx irq flood

2024-04-09T13:57:12Z

The mitigation was intended to stop the irq completely. That may be better than a hard lock-up but it turns out that you get a crash anyway if you're using pmac_zilog as a serial console: ttyPZ0: pmz: rx irq flood ! BUG: spinlock recursion on CPU#0, swapper/0 That's because the pr_err() call in pmz_receive_chars() results in pmz_console_write() attempting to lock a spinlock already locked in pmz_interrupt(). With CONFIG_DEBUG_SPINLOCK=y, this produces a fatal BUG splat. The spinlock in question is the one in struct uart_port. Even when it's not fatal, the serial port rx function ceases to work. Also, the iteration limit doesn't play nicely with QEMU, as can be seen in the bug report linked below. A web search for other reports of the error message "pmz: rx irq flood" didn't produce anything. So I don't think this code is needed any more. Remove it. Cc: Benjamin Herrenschmidt Cc: Michael Ellerman Cc: Nicholas Piggin Cc: Christophe Leroy Cc: Aneesh Kumar K.V Cc: Naveen N. Rao Cc: Andy Shevchenko Cc: stable@kernel.org Cc: linux-m68k@lists.linux-m68k.org Link: https://github.com/vivier/qemu-m68k/issues/44 Link: https://lore.kernel.org/all/1078874617.9746.36.camel@gaston/ Acked-by: Michael Ellerman Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable Signed-off-by: Finn Thain Link: https://lore.kernel.org/r/e853cf2c762f23101cd2ddec0cc0c2be0e72685f.1712568223.git.fthain@linux-m68k.org Signed-off-by: Greg Kroah-Hartman

Merge tag 'tty-6.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

2024-03-21T19:44:10Z

Pull tty / serial driver updates from Greg KH: "Here is the big set of TTY/Serial driver updates and cleanups for 6.9-rc1. Included in here are: - more tty cleanups from Jiri - loads of 8250 driver cleanups from Andy - max310x driver updates - samsung serial driver updates - uart_prepare_sysrq_char() updates for many drivers - platform driver remove callback void cleanups - stm32 driver updates - other small tty/serial driver updates All of these have been in linux-next for a long time with no reported issues" * tag 'tty-6.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (199 commits) dt-bindings: serial: stm32: add power-domains property serial: 8250_dw: Replace ACPI device check by a quirk serial: Lock console when calling into driver before registration serial: 8250_uniphier: Switch to use uart_read_port_properties() serial: 8250_tegra: Switch to use uart_read_port_properties() serial: 8250_pxa: Switch to use uart_read_port_properties() serial: 8250_omap: Switch to use uart_read_port_properties() serial: 8250_of: Switch to use uart_read_port_properties() serial: 8250_lpc18xx: Switch to use uart_read_port_properties() serial: 8250_ingenic: Switch to use uart_read_port_properties() serial: 8250_dw: Switch to use uart_read_port_properties() serial: 8250_bcm7271: Switch to use uart_read_port_properties() serial: 8250_bcm2835aux: Switch to use uart_read_port_properties() serial: 8250_aspeed_vuart: Switch to use uart_read_port_properties() serial: port: Introduce a common helper to read properties serial: core: Add UPIO_UNKNOWN constant for unknown port type serial: core: Move struct uart_port::quirks closer to possible values serial: sh-sci: Call sci_serial_{in,out}() directly serial: core: only stop transmit when HW fifo is empty serial: pch: Use uart_prepare_sysrq_char(). ...

powerpc/macio: Make remove callback of macio driver void returned

2024-03-07T12:06:19Z

Commit fc7a6209d571 ("bus: Make remove callback return void") forces bus_type::remove be void-returned, it doesn't make much sense for any bus based driver implementing remove callbalk to return non-void to its caller. This change is for macio bus based drivers. Signed-off-by: Dawei Li Acked-by: Damien Le Moal Acked-by: Jakub Kicinski Signed-off-by: Michael Ellerman Link: https://msgid.link/TYCP286MB232391520CB471E7C8D6EA84CAD19@TYCP286MB2323.JPNP286.PROD.OUTLOOK.COM

serial: pmac_zilog: Convert to platform remove callback returning void

2024-02-19T08:40:50Z

The .remove() callback for a platform driver returns an int which makes many driver authors wrongly assume it's possible to do error handling by returning an error code. However the value returned is ignored (apart from emitting a warning) and this typically results in resource leaks. To improve here there is a quest to make the remove callback return void. In the first step of this quest all drivers are converted to .remove_new(), which already returns void. Eventually after all drivers are converted, .remove_new() will be renamed to .remove(). Note that pmz_detach() is only called once pmz_attach() was successfully called. In that case platform_set_drvdata() was called and so platform_get_drvdata() won't return NULL. This allows to drop the respective check and so get rid of the only error path in pmz_detach(). After that the driver can be trivially converted from always returning zero in the remove callback to the void returning variant. Signed-off-by: Uwe Kleine-König Link: https://lore.kernel.org/r/90b9a65ad8800b4d047aa5219959008a01588a94.1708246007.git.u.kleine-koenig@pengutronix.de Signed-off-by: Greg Kroah-Hartman

serial: pmac_zilog: Use port lock wrappers

2023-09-18T09:18:13Z

When a serial port is used for kernel console output, then all modifications to the UART registers which are done from other contexts, e.g. getty, termios, are interference points for the kernel console. So far this has been ignored and the printk output is based on the principle of hope. The rework of the console infrastructure which aims to support threaded and atomic consoles, requires to mark sections which modify the UART registers as unsafe. This allows the atomic write function to make informed decisions and eventually to restore operational state. It also allows to prevent the regular UART code from modifying UART registers while printk output is in progress. All modifications of UART registers are guarded by the UART port lock, which provides an obvious synchronization point with the console infrastructure. To avoid adding this functionality to all UART drivers, wrap the spin_[un]lock*() invocations for uart_port::lock into helper functions which just contain the spin_[un]lock*() invocations for now. In a subsequent step these helpers will gain the console synchronization mechanisms. Converted with coccinelle. No functional change. Signed-off-by: Thomas Gleixner Signed-off-by: John Ogness Link: https://lore.kernel.org/r/20230914183831.587273-48-john.ogness@linutronix.de Signed-off-by: Greg Kroah-Hartman

serial: pmac_zilog: Use uart_xmit_advance()

2022-11-03T02:35:42Z

Take advantage of the new uart_xmit_advance() helper. Signed-off-by: Ilpo Järvinen Link: https://lore.kernel.org/r/20221019091151.6692-27-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman

serial: Make ->set_termios() old ktermios const

2022-08-30T12:22:35Z

There should be no reason to adjust old ktermios which is going to get discarded anyway. Reviewed-by: Andy Shevchenko Signed-off-by: Ilpo Järvinen Link: https://lore.kernel.org/r/20220816115739.10928-7-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman

serial: pmac_zilog: remove unused header

2022-06-10T11:33:57Z

After commit a5ddc498e792 (serial: pmac_zilog: remove unfinished DBDMA support), the header is unused and can be removed. So do so. Cc: Michael Ellerman Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Suggested-by: "Ilpo Järvinen" Signed-off-by: Jiri Slaby Link: https://lore.kernel.org/r/20220602083120.22519-1-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman

serial: pmac_zilog: remove initial print

2022-05-19T16:23:19Z

Don't report about the driver when loaded. It's unneeded and frowned upon nowadays. Cc: Michael Ellerman Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Reviewed-by: Ilpo Järvinen Signed-off-by: Jiri Slaby Link: https://lore.kernel.org/r/20220519075653.31356-4-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman

serial: pmac_zilog: remove tracing prints

2022-05-19T16:23:19Z

Remove debug printouts upon function enter/exit. This can be achieved better by tracing. Remove also the one protected by DEBUG_HARD which is not defined anyway. Cc: Michael Ellerman Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Signed-off-by: Jiri Slaby Link: https://lore.kernel.org/r/20220519075653.31356-3-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman