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Daniel Wagner 8afb1d2c12 serial: sh-sci: Use spin_{try}lock_irqsave instead of open coding version Commit `40f70c03e3` ("serial: sh-sci: add locking to console write function to avoid SMP lockup") copied the strategy to avoid locking problems in conjuncture with the console from the UART8250 driver. Instead using directly spin_{try}lock_irqsave(), local_irq_save() followed by spin_{try}lock() was used. While this is correct on mainline, for -rt it is a problem. spin_{try}lock() will check if it is running in a valid context. Since the local_irq_save() has already been executed, the context has changed and spin_{try}lock() will complain. The reason why spin_{try}lock() complains is that on -rt the spin locks are turned into mutexes and therefore can sleep. Sleeping with interrupts disabled is not valid. BUG: sleeping function called from invalid context at /home/wagi/work/rt/v4.4-cip-rt/kernel/locking/rtmutex.c:995 in_atomic(): 0, irqs_disabled(): 128, pid: 778, name: irq/76-eth0 CPU: 0 PID: 778 Comm: irq/76-eth0 Not tainted 4.4.126-test-cip22-rt14-00403-gcd03665c8318 #12 Hardware name: Generic RZ/G1 (Flattened Device Tree) Backtrace: [<c00140a0>] (dump_backtrace) from [<c001424c>] (show_stack+0x18/0x1c) r7:c06b01f0 r6:60010193 r5:00000000 r4:c06b01f0 [<c0014234>] (show_stack) from [<c01d3c94>] (dump_stack+0x78/0x94) [<c01d3c1c>] (dump_stack) from [<c004c134>] (___might_sleep+0x134/0x194) r7:60010113 r6:c06d3559 r5:00000000 r4:ffffe000 [<c004c000>] (___might_sleep) from [<c04ded60>] (rt_spin_lock+0x20/0x74) r5:c06f4d60 r4:c06f4d60 [<c04ded40>] (rt_spin_lock) from [<c02577e4>] (serial_console_write+0x100/0x118) r5:c06f4d60 r4:c06f4d60 [<c02576e4>] (serial_console_write) from [<c0061060>] (call_console_drivers.constprop.15+0x10c/0x124) r10:c06d2894 r9:c04e18b0 r8:00000028 r7:00000000 r6:c06d3559 r5:c06d2798 r4:c06b9914 r3:c02576e4 [<c0060f54>] (call_console_drivers.constprop.15) from [<c0062984>] (console_unlock+0x32c/0x430) r10:c06d30d8 r9:00000028 r8:c06dd518 r7:00000005 r6:00000000 r5:c06d2798 r4:c06d2798 r3:00000028 [<c0062658>] (console_unlock) from [<c0062e1c>] (vprintk_emit+0x394/0x4f0) r10:c06d2798 r9:c06d30ee r8:00000006 r7:00000005 r6:c06a78fc r5:00000027 r4:00000003 [<c0062a88>] (vprintk_emit) from [<c0062fa0>] (vprintk+0x28/0x30) r10:c060bd46 r9:00001000 r8:c06b9a90 r7:c06b9a90 r6:c06b994c r5:c06b9a3c r4:c0062fa8 [<c0062f78>] (vprintk) from [<c0062fb8>] (vprintk_default+0x10/0x14) [<c0062fa8>] (vprintk_default) from [<c009cd30>] (printk+0x78/0x84) [<c009ccbc>] (printk) from [<c025afdc>] (credit_entropy_bits+0x17c/0x2cc) r3:00000001 r2:decade60 r1:c061a5ee r0:c061a523 r4:00000006 [<c025ae60>] (credit_entropy_bits) from [<c025bf74>] (add_interrupt_randomness+0x160/0x178) r10:466e7196 r9:1f536000 r8:fffeef74 r7:00000000 r6:c06b9a60 r5:c06b9a3c r4:dfbcf680 [<c025be14>] (add_interrupt_randomness) from [<c006536c>] (irq_thread+0x1e8/0x248) r10:c006537c r9:c06cdf21 r8:c0064fcc r7:df791c24 r6:df791c00 r5:ffffe000 r4:df525180 [<c0065184>] (irq_thread) from [<c003fba4>] (kthread+0x108/0x11c) r10:00000000 r9:00000000 r8:c0065184 r7:df791c00 r6:00000000 r5:df791d00 r4:decac000 [<c003fa9c>] (kthread) from [<c00101b8>] (ret_from_fork+0x14/0x3c) r8:00000000 r7:00000000 r6:00000000 r5:c003fa9c r4:df791d00 Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Daniel Wagner <daniel.wagner@siemens.com> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2018-05-14 13:51:11 +02:00
arch	Merge 4.17-rc3 into tty-next	2018-04-30 05:14:55 -07:00
block	Revert "blk-mq: remove code for dealing with remapping queue"	2018-04-25 09:49:22 -06:00
certs	certs/blacklist_nohashes.c: fix const confusion in certs blacklist	2018-02-21 15:35:43 -08:00
crypto	crypto: drbg - set freed buffers to NULL	2018-04-21 00:57:00 +08:00
Documentation	tty: serial: qcom_geni_serial: Add early console support	2018-05-14 13:44:55 +02:00
drivers	serial: sh-sci: Use spin_{try}lock_irqsave instead of open coding version	2018-05-14 13:51:11 +02:00
firmware	kbuild: remove all dummy assignments to obj-	2017-11-18 11:46:06 +09:00
fs	Fix misc. bugs and a regression for ext4.	2018-04-28 20:07:21 -07:00
include	Merge 4.17-rc3 into tty-next	2018-04-30 05:14:55 -07:00
init	Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2018-04-15 16:12:35 -07:00
ipc	ipc/shm: fix use-after-free of shm file via remap_file_pages()	2018-04-13 17:10:27 -07:00
kernel	Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2018-04-29 09:03:25 -07:00
lib	Driver core fixes for 4.17-rc3	2018-04-27 10:12:20 -07:00
LICENSES	LICENSES: Add MPL-1.1 license	2018-01-06 10:59:44 -07:00
mm	x86/pti: Filter at vma->vm_page_prot population	2018-04-25 11:02:51 +02:00
net	A CephFS quota follow-up and fixes for two older issues in the	2018-04-27 10:56:29 -07:00
samples	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching	2018-04-20 08:51:55 -07:00
scripts	Kbuild updates for v4.17 (2nd)	2018-04-15 17:21:30 -07:00
security	Merge branch 'userns-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace	2018-04-24 17:58:51 -07:00
sound	ALSA: dice: fix error path to destroy initialized stream data	2018-04-26 15:24:54 +02:00
tools	Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2018-04-29 09:36:22 -07:00
usr	kbuild: rename built-in.o to built-in.a	2018-03-26 02:01:19 +09:00
virt	KVM fixes for v4.17-rc3	2018-04-27 16:13:31 -07:00
.clang-format	clang-format: add configuration file	2018-04-11 10:28:35 -07:00
.cocciconfig
.get_maintainer.ignore
.gitattributes	.gitattributes: set git diff driver for C source code files	2016-10-07 18:46:30 -07:00
.gitignore	Kbuild updates for v4.17 (2nd)	2018-04-15 17:21:30 -07:00
.mailmap	Merge candidates for 4.17 merge window	2018-04-06 17:35:43 -07:00
COPYING	COPYING: use the new text with points to the license files	2018-03-23 12:41:45 -06:00
CREDITS	MAINTAINERS/CREDITS: Drop METAG ARCHITECTURE	2018-03-05 16:34:24 +00:00
Kbuild	Kbuild updates for v4.15	2017-11-17 17:45:29 -08:00
Kconfig	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
MAINTAINERS	MAINTAINERS: add myself as maintainer of AFFS	2018-04-28 10:30:47 -07:00
Makefile	Linux v4.17-rc3	2018-04-29 14:17:42 -07:00
README	Docs: Added a pointer to the formatted docs to README	2018-03-21 09:02:53 -06:00

README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.