- 05 Oct, 2012 40 commits
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Wei Yongjun authored
Convert cpu_to_leXX(leXX_to_cpu(E1) + E2) to use leXX_add_cpu(). dpatch engine is used to auto generate this patch. (https://github.com/weiyj/dpatch) Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn> Cc: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Michael Langer authored
Add basic get/set alarm support for the Seiko Instruments S-35390A. The chip is used on the QNAP TS-219P+ NAS device. Signed-off-by: Michael Langer <michael.brainbug.langer@googlemail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Paul Bolle authored
Commit c3b79770 ("rtc: m41t80: Workaround broken alarm functionality") disabled m41t80's alarm functions. But since those functions were not touched, building this driver triggers these GCC warnings: drivers/rtc/rtc-m41t80.c:216:12: warning: 'm41t80_rtc_alarm_irq_enable' defined but not used [-Wunused-function] drivers/rtc/rtc-m41t80.c:238:12: warning: 'm41t80_rtc_set_alarm' defined but not used [-Wunused-function] drivers/rtc/rtc-m41t80.c:308:12: warning: 'm41t80_rtc_read_alarm' defined but not used [-Wunused-function] Remove these functions (and the commented out references to them) to silence these warnings. Anyone wanting to fix the alarm irq functionality can easily find the removed code in the git log of this file or through some web searches. Signed-off-by: Paul Bolle <pebolle@tiscali.nl> Cc: John Stultz <john.stultz@linaro.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Venu Byravarasu authored
As RTC driver needs only irq number from platform data, using platform_get_irq(), instead of generic dev_get_platdata(). Signed-off-by: Venu Byravarasu <vbyravarasu@nvidia.com> Acked-by: Stephen Warren <swarren@wwwdotorg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Ulf Hansson authored
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> Acked-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Shubhrajyoti D authored
Convert the struct i2c_msg initialization to C99 format. This makes maintaining and editing the code simpler. Also helps once other fields like transferred are added in future. Signed-off-by: Shubhrajyoti D <shubhrajyoti@ti.com> Reviewed-by: Felipe Balbi <balbi@ti.com> Cc: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Shubhrajyoti D authored
Convert the struct i2c_msg initialization to C99 format. This makes maintaining and editing the code simpler. Also helps once other fields like transferred are added in future. Signed-off-by: Shubhrajyoti D <shubhrajyoti@ti.com> Reviewed-by: Felipe Balbi <balbi@ti.com> Cc: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Shubhrajyoti D authored
Convert the struct i2c_msg initialization to C99 format. This makes maintaining and editing the code simpler. Also helps once other fields like transferred are added in future. Signed-off-by: Shubhrajyoti D <shubhrajyoti@ti.com> Reviewed-by: Felipe Balbi <balbi@ti.com> Cc: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Shubhrajyoti D authored
Convert the struct i2c_msg initialization to C99 format. This makes maintaining and editing the code simpler. Also helps once other fields like transferred are added in future. while at it also fix a checkpatch warn WARNING: sizeof rs5c->buf should be sizeof(rs5c->buf) Signed-off-by: Shubhrajyoti D <shubhrajyoti@ti.com> Reviewed-by: Felipe Balbi <balbi@ti.com> Cc: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Shubhrajyoti D authored
Convert the struct i2c_msg initialization to C99 format. This makes maintaining and editing the code simpler. Also helps once other fields like transferred are added in future. Signed-off-by: Shubhrajyoti D <shubhrajyoti@ti.com> Reviewed-by: Felipe Balbi <balbi@ti.com> Cc: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Shubhrajyoti D authored
Convert the struct i2c_msg initialization to C99 format. This makes maintaining and editing the code simpler. Also helps once other fields like transferred are added in future. Signed-off-by: Shubhrajyoti D <shubhrajyoti@ti.com> Reviewed-by: Felipe Balbi <balbi@ti.com> Cc: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Shubhrajyoti D authored
Convert the struct i2c_msg initialization to C99 format. This makes maintaining and editing the code simpler. Also helps once other fields like transferred are added in future. Signed-off-by: Shubhrajyoti D <shubhrajyoti@ti.com> Reviewed-by: Felipe Balbi <balbi@ti.com> Cc: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Sachin Kamat authored
Return the value returned by platform_get_irq() instead of -ENOENT; Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org> Cc: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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David Fries authored
Without this patch /sys/class/rtc/$CONFIG_RTC_HCTOSYS_DEVICE/hctosys contains a 1 (meaning "This rtc was used to initialize the system clock") even if setting the time by do_settimeofday() at bootup failed. The RTC can also be used to set the clock on resume, if it did 1, otherwise 0. Previously there was no indication if the RTC was used to set the clock in resume. This uses only CONFIG_RTC_HCTOSYS_DEVICE for conditional compilation instead of it and CONFIG_RTC_HCTOSYS to be more consistent. rtc_hctosys_ret was moved to class.c so class.c no longer depends on hctosys.c. [sfr@canb.auug.org.au: fix build] Signed-off-by: David Fries <David@Fries.net> Cc: Matthew Garrett <mjg@redhat.com> Cc: Alessandro Zummo <a.zummo@towertech.it> Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Fabio Estevam authored
Converting to module_platform_driver can make the code smaller and cleaner. Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com> Cc: Sascha Hauer <s.hauer@pengutronix.de> Cc: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Fabio Estevam authored
i.mx drivers should use clk_prepare_enable/clk_disable_unprepare() in order to avoid clk warnings. While at it, convert to devm_clk_get() since other devm_ functions are used in this driver and it can also save some clk_put() calls. Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com> Acked-by: Sascha Hauer <s.hauer@pengutronix.de> Cc: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Julia Lawall authored
clk_prepare_enable and clk_disable_unprepare combine clk_prepare and clk_enable, and clk_disable and clk_unprepare. They make the code more concise, and ensure that clk_unprepare is called when clk_enable fails. A simplified version of the semantic patch that introduces calls to these functions is as follows: (http://coccinelle.lip6.fr/) // <smpl> @@ expression e; @@ - clk_prepare(e); - clk_enable(e); + clk_prepare_enable(e); @@ expression e; @@ - clk_disable(e); - clk_unprepare(e); + clk_disable_unprepare(e); // </smpl> Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr> Acked-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Venu Byravarasu authored
Add an RTC driver for the RTC device on Ricoh MFD Rc5t583. Ricoh RTC has 3 types of alarms. The current patch adds support for the Y-Alarm of RC5t583 RTC. Signed-off-by: Venu Byravarasu <vbyravarasu@nvidia.com> Cc: Alessandro Zummo <a.zummo@towertech.it> Cc: Mark Brown <broonie@opensource.wolfsonmicro.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Lars-Peter Clausen authored
There are several comparisons of a unsigned int to less than zero int spear RTC driver. Such a check will always be true. In all these cases a signed int is assigned to the unsigned variable, which is checked, before. So the right fix is to make the checked variable signed as well. In one case the check can be dropped completely, because all it does it returns 'err' if 'err' is less than zero, otherwise it returns 0. Since in this particular case 'err' is always either 0 or less this is the same as just returning 'err'. The issue has been found using the following coccinelle semantic patch: //<smpl> @@ type T; unsigned T i; @@ ( *i < 0 | *i >= 0 ) //</smpl> Signed-off-by: Lars-Peter Clausen <lars@metafoo.de> Cc: Viresh Kumar <viresh.kumar@st.com> Cc: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Lars-Peter Clausen authored
The irq field of the jz4740_irc struct is unsigned. Yet we assign the result of platform_get_irq() to it. platform_get_irq() may return a negative error code and the code checks for this condition by checking if 'irq' is less than zero. But since 'irq' is unsigned this test will always be false. Fix it by making 'irq' signed. The issue was found using the following coccinelle semantic patch: //<smpl> @@ type T; unsigned T i; @@ ( *i < 0 | *i >= 0 ) //</smpl> Signed-off-by: Lars-Peter Clausen <lars@metafoo.de> Cc: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Venu Byravarasu authored
Remove "depends on RTC_CLASS = y" for multiple Kconfig definitions, as all of them are already placed under "if RTC_CLASS". Signed-off-by: Venu Byravarasu <vbyravarasu@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Stephen Warren authored
The MAX8907 is an I2C-based power-management IC containing voltage regulators, a reset controller, a real-time clock, and a touch-screen controller. The driver is based on an original by or fixed by: * Tom Cherry * Prashant Gaikwad * Joseph Yoon During upstreaming, I (swarren): * Converted to regmap. * Fixed handling of RTC_HOUR register containing 12. * Fixed handling of RTC_WEEKDAY register. * General cleanup. Signed-off-by: Stephen Warren <swarren@nvidia.com> Cc: Tom Cherry <tcherry@nvidia.com> Cc: Prashant Gaikwad <pgaikwad@nvidia.com> Cc: Joseph Yoon <tyoon@nvidia.com> Cc: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Venu Byravarasu authored
TPS65910 PMIC is a MFD with RTC as one of the device. Adding RTC driver for supporting RTC device present inside TPS65910 PMIC. Only support for RTC alarm is implemented as part of this patch. Signed-off-by: Venu Byravarasu <vbyravarasu@nvidia.com> Cc: Alessandro Zummo <a.zummo@towertech.it> Cc: Mark Brown <broonie@opensource.wolfsonmicro.com> Cc: Samuel Ortiz <sameo@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Devendra Naga authored
This driver does seems to do only platform_driver_register in the init function and platform_driver_unregister in the exit function, so replace all this code including the module_init and module_exit with module_platform_driver macro... Signed-off-by: Devendra Naga <develkernel412222@gmail.com> Cc: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Vincent Palatin authored
When calling rtc_device_unregister, we are not freeing the id used by the driver. So when doing a unload/load cycle for a RTC driver (e.g. rmmod rtc_cmos && modprobe rtc_cmos), its id is incremented by one. As a consequence, we no longer have neither an rtc0 driver nor a /proc/driver/rtc (as it only exists for the first driver). Signed-off-by: Vincent Palatin <vpalatin@chromium.org> Cc: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Shawn Guo authored
Add an RTC driver for Freescale Secure Non-Volatile Storage (SNVS) Low Power (LP) RTC. Signed-off-by: Shawn Guo <shawn.guo@linaro.org> Reviewed-by: Stephen Boyd <sboyd@codeaurora.org> Cc: Alessandro Zummo <a.zummo@towertech.it> Cc: Kim Phillips <kim.phillips@freescale.com> Cc: Sascha Hauer <s.hauer@pengutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Sven Schnelle authored
[akpm@linux-foundation.org: fix warning] Signed-off-by: Sven Schnelle <svens@stackframe.org> Cc: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Kim, Milo authored
To get time information via /proc/driver/rtc, only the first device (rtc0) is used. If the rtcN (eg. rtc1 or rtc2) is used for the system clock, there is no way to get information of rtcN via /proc/driver/rtc. With this patch, the time data can be retrieved from the system clock RTC. If the RTC_HCTOSYS_DEVICE is not defined, then rtc0 is used by default. Signed-off-by: Milo(Woogyom) Kim <milo.kim@ti.com> Cc: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Ben Gardner authored
The ISL1218 chip is identical to the ISL1208, except that it has 6 additional user-storage registers. This patch does not enable access to those additional registers, but only adds the chip name to the list. Signed-off-by: Ben Gardner <gardner.ben@gmail.com> Cc: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Alan Cox authored
load_elf_interp() has interp_map_addr carefully described as "uninitialized_var" and marked so as to avoid a warning. However if you trace the code it is passed into load_elf_interp and then this value is checked against NULL. As this return value isn't used this is actually safe but it freaks various analysis tools that see un-initialized memory addresses being read before their value is ever defined. Set it to NULL as a matter of programming good taste if nothing else Signed-off-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Paton J. Lewis authored
Enhanced epoll_ctl to support EPOLL_CTL_DISABLE, which disables an epoll item. If epoll_ctl doesn't return -EBUSY in this case, it is then safe to delete the epoll item in a multi-threaded environment. Also added a new test_epoll self- test app to both demonstrate the need for this feature and test it. Signed-off-by: Paton J. Lewis <palewis@adobe.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Jason Baron <jbaron@redhat.com> Cc: Paul Holland <pholland@adobe.com> Cc: Davide Libenzi <davidel@xmailserver.org> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Kees Cook authored
Fix macro name in checkpatch: s/PARAM/PARM/. Signed-off-by: Kees Cook <keescook@chromium.org> Cc: Joe Perches <joe@perches.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Joe Perches authored
The block comment style in net/ and drivers/net is non-standard. Document it. Signed-off-by: Joe Perches <joe@perches.com> Cc: "Allan, Bruce W" <bruce.w.allan@intel.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: David Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Joe Perches authored
In an effort to get fewer checkpatch reviewer corrections, add a networking specific style test for the preferred networking comment style. /* The preferred style for block comments in * drivers/net/... and net/... is like this */ These tests are only used in net/ and drivers/net/ Tested with: $ cat drivers/net/t.c /* foo */ /* * foo */ /* foo */ /* foo * bar */ $ ./scripts/checkpatch.pl -f drivers/net/t.c WARNING: networking block comments don't use an empty /* line, use /* Comment... #4: FILE: net/t.c:4: + +/* WARNING: networking block comments put the trailing */ on a separate line #12: FILE: net/t.c:12: + * bar */ total: 0 errors, 2 warnings, 12 lines checked Signed-off-by: Joe Perches <joe@perches.com> Cc: "Allan, Bruce W" <bruce.w.allan@intel.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: David Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Joe Perches authored
Direct conversion of printk(KERN_<LEVEL>... to pr_<level> isn't the preferred conversion when a struct net_device or struct device is available. Hint that using netdev_<level> or dev_<level> is preferred to using pr_<level>. Add netdev_dbg and dev_dbg variants too. Miscellaneous whitespace neatening of a misplaced close brace. Signed-off-by: Joe Perches <joe@perches.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Pasi Savanainen authored
Check that a commit log doesn't contain UTF-8 when a mail header explicitly defines a different charset, like 'Content-Type: text/plain; charset="us-ascii"' Signed-off-by: Pasi Savanainen <pasi.savanainen@nixu.com> Cc: Joe Perches <joe@perches.com> Cc: Andy Whitcroft <apw@canonical.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Tejun Heo authored
SG mapping iterator w/ SG_MITER_ATOMIC set required IRQ disabled because it originally used KM_BIO_SRC_IRQ to allow use from IRQ handlers. kmap_atomic() has long been updated to handle stacking atomic mapping requests on per-cpu basis and only requires not sleeping while mapped. Update sg_mapping_iter such that atomic iterators only require disabling preemption instead of disabling IRQ. While at it, convert wte weird @ARG@ notations to @ARG in the comment of sg_miter_start(). Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Maxim Levitsky <maximlevitsky@gmail.com> Cc: Alex Dubov <oakad@yahoo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Borislav Petkov authored
They show up in dmesg [ 4.041094] start plist test [ 4.045804] end plist test without a lot of meaning so hide them behind debug loglevel. Signed-off-by: Borislav Petkov <borislav.petkov@amd.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Acked-by: Steven Rostedt <rostedt@goodmis.org> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Jan Beulich authored
Xen's pciback points out a couple of deficiencies with vsscanf()'s standard conformance: - Trailing character matching cannot be checked by the caller: With a format string of "(%x:%x.%x) %n" absence of the closing parenthesis cannot be checked, as input of "(00:00.0)" doesn't cause the %n to be evaluated (because of the code not skipping white space before the trailing %n). - The parameter corresponding to a trailing %n could get filled even if there was a matching error: With a format string of "(%x:%x.%x)%n", input of "(00:00.0]" would still fill the respective variable pointed to (and hence again make the mismatch non-detectable by the caller). This patch aims at fixing those, but leaves other non-conforming aspects of it untouched, among them these possibly relevant ones: - improper handling of the assignment suppression character '*' (blindly discarding all succeeding non-white space from the format and input strings), - not honoring conversion specifiers for %n, - not recognizing the C99 conversion specifier 't' (recognized by vsprintf()). Signed-off-by: Jan Beulich <jbeulich@suse.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Vikram Mulukutla authored
The logic in do_raw_spin_lock() attempts to acquire a spinlock by invoking arch_spin_trylock() in a loop with a delay between each attempt. Now consider the following situation in a 2 CPU system: 1. CPU-0 continually acquires and releases a spinlock in a tight loop; it stays in this loop until some condition X is satisfied. X can only be satisfied by another CPU. 2. CPU-1 tries to acquire the same spinlock, in an attempt to satisfy the aforementioned condition X. However, it never sees the unlocked value of the lock because the debug spinlock code uses trylock instead of just lock; it checks at all the wrong moments - whenever CPU-0 has locked the lock. Now in the absence of debug spinlocks, the architecture specific spinlock code can correctly allow CPU-1 to wait in a "queue" (e.g., ticket spinlocks), ensuring that it acquires the lock at some point. However, with the debug spinlock code, livelock can easily occur due to the use of try_lock, which obviously cannot put the CPU in that "queue". This queueing mechanism is implemented in both x86 and ARM spinlock code. Note that the situation mentioned above is not hypothetical. A real problem was encountered where CPU-0 was running hrtimer_cancel with interrupts disabled, and CPU-1 was attempting to run the hrtimer that CPU-0 was trying to cancel. Address this by actually attempting arch_spin_lock once it is suspected that there is a spinlock lockup. If we're in a situation that is described above, the arch_spin_lock should succeed; otherwise other timeout mechanisms (e.g., watchdog) should alert the system of a lockup. Therefore, if there is a genuine system problem and the spinlock can't be acquired, the end result (irrespective of this change being present) is the same. If there is a livelock caused by the debug code, this change will allow the lock to be acquired, depending on the implementation of the lower level arch specific spinlock code. [akpm@linux-foundation.org: tweak comment] Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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