linux.git/drivers/tty/serial/mpsc.c, branch v3.15

serial: mpsc: Remove casting the return value which is a void pointer

2013-09-26T21:29:58+00:00

Casting the return value which is a void pointer is redundant.
The conversion from void pointer to any other pointer type is
guaranteed by the C programming language.

Signed-off-by: Jingoo Han 
Acked-by: Vineet Gupta 
Signed-off-by: Greg Kroah-Hartman

tty: serial: mpsc: drop uart_port->lock before calling tty_flip_buffer_push()

2013-08-27T23:17:34+00:00

The current driver triggers a lockdep warning for if tty_flip_buffer_push() is
called with uart_port->lock locked. This never shows up on UP kernels and comes
up only on SMP kernels.

Crash looks like this (produced with samsung.c driver):

-----
[] (unwind_backtrace+0x0/0xf8) from [] (show_stack+0x10/0x14)
[] (show_stack+0x10/0x14) from [] (dump_stack+0x6c/0xac)
[] (dump_stack+0x6c/0xac) from [] (do_raw_spin_unlock+0xc4/0xd8)
[] (do_raw_spin_unlock+0xc4/0xd8) from [] (_raw_spin_unlock_irqrestore+0xc/0)
[] (_raw_spin_unlock_irqrestore+0xc/0x38) from [] (s3c24xx_serial_rx_chars+0)
[] (s3c24xx_serial_rx_chars+0x12c/0x260) from [] (s3c64xx_serial_handle_irq+)
[] (s3c64xx_serial_handle_irq+0x48/0x60) from [] (handle_irq_event_percpu+0x)
[] (handle_irq_event_percpu+0x50/0x194) from [] (handle_irq_event+0x3c/0x5c)
[] (handle_irq_event+0x3c/0x5c) from [] (handle_fasteoi_irq+0x80/0x13c)
[] (handle_fasteoi_irq+0x80/0x13c) from [] (generic_handle_irq+0x20/0x30)
[] (generic_handle_irq+0x20/0x30) from [] (handle_IRQ+0x38/0x94)
[] (handle_IRQ+0x38/0x94) from [] (gic_handle_irq+0x34/0x68)
[] (gic_handle_irq+0x34/0x68) from [] (__irq_svc+0x40/0x70)
Exception stack(0xc04cdf70 to 0xc04cdfb8)
df60:                                     00000000 00000000 0000166e 00000000
df80: c04cc000 c050278f c050278f 00000001 c04d444c 410fc0f4 c03649b0 00000000
dfa0: 00000001 c04cdfb8 c000f758 c000f75c 60070013 ffffffff
[] (__irq_svc+0x40/0x70) from [] (arch_cpu_idle+0x28/0x30)
[] (arch_cpu_idle+0x28/0x30) from [] (cpu_startup_entry+0x5c/0x148)
[] (cpu_startup_entry+0x5c/0x148) from [] (start_kernel+0x334/0x38c)
BUG: spinlock lockup suspected on CPU#0, kworker/0:1/360
 lock: s3c24xx_serial_ports+0x1d8/0x370, .magic: dead4ead, .owner: /-1, .owner_cpu: -1
CPU: 0 PID: 360 Comm: kworker/0:1 Not tainted 3.11.0-rc6-next-20130819-00003-g75485f1 #2
Workqueue: events flush_to_ldisc
[] (unwind_backtrace+0x0/0xf8) from [] (show_stack+0x10/0x14)
[] (show_stack+0x10/0x14) from [] (dump_stack+0x6c/0xac)
[] (dump_stack+0x6c/0xac) from [] (do_raw_spin_lock+0x100/0x17c)
[] (do_raw_spin_lock+0x100/0x17c) from [] (_raw_spin_lock_irqsave+0x20/0x28)
[] (_raw_spin_lock_irqsave+0x20/0x28) from [] (uart_start+0x18/0x34)
[] (uart_start+0x18/0x34) from [] (__receive_buf+0x4b4/0x738)
[] (__receive_buf+0x4b4/0x738) from [] (n_tty_receive_buf2+0x30/0x98)
[] (n_tty_receive_buf2+0x30/0x98) from [] (flush_to_ldisc+0xec/0x138)
[] (flush_to_ldisc+0xec/0x138) from [] (process_one_work+0xfc/0x348)
[] (process_one_work+0xfc/0x348) from [] (worker_thread+0x138/0x37c)
[] (worker_thread+0x138/0x37c) from [] (kthread+0xa4/0xb0)
[] (kthread+0xa4/0xb0) from [] (ret_from_fork+0x14/0x3c)
-----

Release the port lock before calling tty_flip_buffer_push() and reacquire it
after the call.

Similar stuff was already done for few other drivers in the past, like:

commit 2389b272168ceec056ca1d8a870a97fa9c26e11a
Author: Thomas Gleixner 
Date:   Tue May 29 21:53:50 2007 +0100

    [ARM] 4417/1: Serial: Fix AMBA drivers locking

Signed-off-by: Viresh Kumar 
Signed-off-by: Greg Kroah-Hartman

serial: use dev_get_platdata()

2013-08-01T00:56:15+00:00

Use the wrapper function for retrieving the platform data instead of
accessing dev->platform_data directly.

Signed-off-by: Jingoo Han 
Signed-off-by: Greg Kroah-Hartman

TTY: switch tty_flip_buffer_push

2013-01-16T06:30:15+00:00

Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty in many
call sites. Only tty_port will needed and hence no more
tty_port_tty_get in those paths.

Now, the one where most of tty_port_tty_get gets removed:
tty_flip_buffer_push.

IOW we also closed all the races in drivers not using tty_port_tty_get
at all yet.

Also we move tty_flip_buffer_push declaration from include/linux/tty.h
to include/linux/tty_flip.h to all others while we are changing it
anyway.

Signed-off-by: Jiri Slaby 
Signed-off-by: Greg Kroah-Hartman

TTY: move low_latency to tty_port

2013-01-16T06:23:16+00:00

One point is to have less places where we actually need tty pointer.
The other is that low_latency is bound to buffer processing and
buffers are now in tty_port. So it makes sense to move low_latency to
tty_port too.

Signed-off-by: Jiri Slaby 
Signed-off-by: Greg Kroah-Hartman

TTY: switch tty_insert_flip_char

2013-01-16T06:21:36+00:00

Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty in many
call sites. Only tty_port will needed and hence no more
tty_port_tty_get in those paths.

tty_insert_flip_char is the next one to proceed. This one is used all
over the code, so the patch is huge.

Signed-off-by: Jiri Slaby 
Signed-off-by: Greg Kroah-Hartman

TTY: switch tty_buffer_request_room to tty_port

2013-01-16T06:17:28+00:00

Now, we start converting tty buffer functions to actually use
tty_port. This will allow us to get rid of the need of tty pointer in
many call sites. Only tty_port will be needed and hence no more
tty_port_tty_get calls in those paths.

Here we start with tty_buffer_request_room.

Signed-off-by: Jiri Slaby 
Signed-off-by: Greg Kroah-Hartman

tty: move drivers/serial/ to drivers/tty/serial/

2011-01-13T20:10:18+00:00

The serial drivers are really just tty drivers, so move them to
drivers/tty/ to make things a bit neater overall.

This is part of the tty/serial driver movement proceedure as proposed by
Arnd Bergmann and approved by everyone involved a number of months ago.

Cc: Arnd Bergmann 
Cc: Alan Cox 
Cc: Geert Uytterhoeven 
Cc: Rogier Wolff 
Cc: Michael H. Warfield 
Signed-off-by: Greg Kroah-Hartman