- 16 Oct, 2019 1 commit
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Thomas Bogendoerfer authored
SGI Octane (IP30) doesn't have RTC register directly mapped into CPU address space, but accesses RTC registers with an address and data register. This is now supported by additional access functions, which are selected by a new field in platform data. Removed plat_read/plat_write since there is no user and their usage could introduce lifetime issue, when functions are placed in different modules. Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de> Acked-by: Joshua Kinard <kumba@gentoo.org> Reviewed-by: Joshua Kinard <kumba@gentoo.org> Link: https://lore.kernel.org/r/20191014214621.25257-1-tbogendoerfer@suse.deSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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- 14 Oct, 2019 4 commits
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Thomas Bogendoerfer authored
Simplify ioremapping of registers by using devm_platform_ioremap_resource. Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de> Acked-by: Joshua Kinard <kumba@gentoo.org> Link: https://lore.kernel.org/r/20191011150546.9186-2-tbogendoerfer@suse.deSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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Thomas Bogendoerfer authored
A few of the fields in struct ds1685_priv aren't needed at all, so we can remove it. Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de> Acked-by: Joshua Kinard <kumba@gentoo.org> Link: https://lore.kernel.org/r/20191011150546.9186-1-tbogendoerfer@suse.deSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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Srinivas Goud authored
This patch fixes the warnings reported by static code analysis. Updated calibval variable type to unsigned type from signed. Signed-off-by: Srinivas Goud <srinivas.goud@xilinx.com> Signed-off-by: Michal Simek <michal.simek@xilinx.com> Link: https://lore.kernel.org/r/20765c4c27aa92c75426b82fd2815ebef6471492.1570544738.git.michal.simek@xilinx.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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Nick Crews authored
If the RTC HW returns an invalid time, the rtc_year_days() call would crash. This patch adds error logging in this situation, and removes the tm_yday and tm_wday calculations. These fields should not be relied upon by userspace according to man rtc, and thus we don't need to calculate them. Signed-off-by: Nick Crews <ncrews@chromium.org> Reviewed-by: Daniel Campello <campello@chromium.org> Link: https://lore.kernel.org/r/20191004142608.170159-1-ncrews@chromium.orgSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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- 07 Oct, 2019 13 commits
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Alexandre Belloni authored
The DS1347 can handle years from 0 to 9999, add century register support. Link: https://lore.kernel.org/r/20191007134724.15505-10-alexandre.belloni@bootlin.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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Alexandre Belloni authored
Use regmap_update_bits instead of open coding. Also add proper error handling. Link: https://lore.kernel.org/r/20191007134724.15505-9-alexandre.belloni@bootlin.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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Alexandre Belloni authored
The comment in the probe function stating that it disables oscillator stop detection and glitch filtering is incorrect as it sets bits 3 and 4 while it should be setting 5 and 6 to achieve that. Then, it is safe to assume that the oscillator failure detection is actually enabled. Properly handle oscillator failures by returning -EINVAL when the time and date are know to be incorrect and reset the flag when the time is set. Link: https://lore.kernel.org/r/20191007134724.15505-8-alexandre.belloni@bootlin.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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Alexandre Belloni authored
The DS1347 handle dates from year 0000 to 9999. Leap years are claimed to be handled correctly in the datasheet. Link: https://lore.kernel.org/r/20191007134724.15505-7-alexandre.belloni@bootlin.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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Alexandre Belloni authored
This allows further improvement of the driver. Link: https://lore.kernel.org/r/20191007134724.15505-6-alexandre.belloni@bootlin.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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Alexandre Belloni authored
Bit 7 of the minutes registers is ALM OUT. It indicates an alarm fired. Mask it out when reading the time. Link: https://lore.kernel.org/r/20191007134724.15505-5-alexandre.belloni@bootlin.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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Alexandre Belloni authored
Get 'driver_data' from 'struct device' directly. Going via spi_device is an unnecessary step. Link: https://lore.kernel.org/r/20191007134724.15505-4-alexandre.belloni@bootlin.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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Alexandre Belloni authored
DS1347_SECONDS_REG is read at probe time but the value is simply discarded. Remove that useless read. Link: https://lore.kernel.org/r/20191007134724.15505-3-alexandre.belloni@bootlin.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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Alexandre Belloni authored
Printing debugging (and opaque) information is not useful and only clutters the boot log. Remove those messages. Link: https://lore.kernel.org/r/20191007134724.15505-2-alexandre.belloni@bootlin.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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Alexandre Belloni authored
A few RTCs handle dates from year 0 to year 9999. Add a timestamp even if years before 1970 will probably never be used. Link: https://lore.kernel.org/r/20191007134724.15505-1-alexandre.belloni@bootlin.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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Stephen Boyd authored
Use the more modern API to get the match data out of the of match table. This saves some code, lines, and nicely avoids referencing the match table when it is undefined with configurations where CONFIG_OF=n. Cc: Arnd Bergmann <arnd@arndb.de> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Jason Cooper <jason@lakedaemon.net> Cc: Andrew Lunn <andrew@lunn.ch> Cc: Gregory Clement <gregory.clement@bootlin.com> Cc: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com> Cc: Alessandro Zummo <a.zummo@towertech.it> Cc: Alexandre Belloni <alexandre.belloni@bootlin.com> Cc: Rob Herring <robh+dt@kernel.org> Cc: Frank Rowand <frowand.list@gmail.com> Cc: <linux-rtc@vger.kernel.org> Signed-off-by: Stephen Boyd <swboyd@chromium.org> Link: https://lore.kernel.org/r/20191004214334.149976-4-swboyd@chromium.orgSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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Krzysztof Kozlowski authored
platform_get_irq_byname() might return -errno which later would be cast to an unsigned int and used in request_irq(). Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org> Tested-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com> Link: https://lore.kernel.org/r/20191004150510.6278-1-krzk@kernel.orgSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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Alexandre Belloni authored
This is a standard BCD RTC that will fail in 2100. The century bits don't help because 2100 will be considered a leap year while it is not. Link: https://lore.kernel.org/r/20191003213544.5359-1-alexandre.belloni@bootlin.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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- 06 Oct, 2019 2 commits
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YueHaibing authored
Use devm_platform_ioremap_resource() to simplify the code a bit. This is detected by coccinelle. Signed-off-by: YueHaibing <yuehaibing@huawei.com> Link: https://lore.kernel.org/r/20191006102953.57536-2-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-3-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-4-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-5-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-6-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-7-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-8-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-9-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-10-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-11-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-12-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-13-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-14-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-15-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-16-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-17-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-18-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-19-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-20-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-21-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-22-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-23-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-24-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-25-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-26-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-27-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-28-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-29-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-30-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-31-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-32-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-33-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-34-yuehaibing@huawei.com Link: https://lore.kernel.org/r/20191006102953.57536-35-yuehaibing@huawei.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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Markus Elfring authored
Simplify probe by using a known wrapper function. This issue was detected by using the Coccinelle software. Signed-off-by: Markus Elfring <elfring@users.sourceforge.net> Link: https://lore.kernel.org/r/4552ef52-f218-93b1-6dfa-668d137676f8@web.de Link: https://lore.kernel.org/r/5ecfcf43-d6b2-1a38-dee8-b8806f30bc83@web.de Link: https://lore.kernel.org/r/25448e11-c43f-9ae0-4c43-6f789accc026@web.deReviewed-by: Akinobu Mita <akinobu.mita@gmail.com> Link: https://lore.kernel.org/r/8c17a59c-82ff-aa6b-5653-a38d786d3e83@web.deSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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- 03 Oct, 2019 2 commits
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Emmanuel Nicolet authored
For rtc drivers where rtc->range_max is set U64_MAX, like the PS3 rtc, rtc_valid_range() always returns -ERANGE. This is because the local variable range_max has type time64_t, so the test if (time < range_min || time > range_max) return -ERANGE; becomes (time < range_min || time > -1), which always evaluates to true. timeu64_t should be used, since it's the type of rtc->range_max. Signed-off-by: Emmanuel Nicolet <emmanuel.nicolet@gmail.com> Link: https://lore.kernel.org/r/20190927110446.GA6289@gmail.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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Claudiu Beznea authored
Use of_device_get_match_data() since all platforms should now use DT bindings. AVR32 architecture has been removed in commit 26202873 ("avr32: remove support for AVR32 architecture"). Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com> Link: https://lore.kernel.org/r/1569500132-21164-1-git-send-email-claudiu.beznea@microchip.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
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- 30 Sep, 2019 17 commits
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Linus Torvalds authored
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git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linuxLinus Torvalds authored
Pull btrfs fixes from David Sterba: "A bunch of fixes that accumulated in recent weeks, mostly material for stable. Summary: - fix for regression from 5.3 that prevents to use balance convert with single profile - qgroup fixes: rescan race, accounting leak with multiple writers, potential leak after io failure recovery - fix for use after free in relocation (reported by KASAN) - other error handling fixups" * tag 'for-5.4-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: btrfs: qgroup: Fix reserved data space leak if we have multiple reserve calls btrfs: qgroup: Fix the wrong target io_tree when freeing reserved data space btrfs: Fix a regression which we can't convert to SINGLE profile btrfs: relocation: fix use-after-free on dead relocation roots Btrfs: fix race setting up and completing qgroup rescan workers Btrfs: fix missing error return if writeback for extent buffer never started btrfs: adjust dirty_metadata_bytes after writeback failure of extent buffer Btrfs: fix selftests failure due to uninitialized i_mode in test inodes
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git://github.com/c-sky/csky-linuxLinus Torvalds authored
Pull csky updates from Guo Ren: "This round of csky subsystem just some fixups: - Fix mb() synchronization problem - Fix dma_alloc_coherent with PAGE_SO attribute - Fix cache_op failed when cross memory ZONEs - Optimize arch_sync_dma_for_cpu/device with dma_inv_range - Fix ioremap function losing - Fix arch_get_unmapped_area() implementation - Fix defer cache flush for 610 - Support kernel non-aligned access - Fix 610 vipt cache flush mechanism - Fix add zero_fp fixup perf backtrace panic - Move static keyword to the front of declaration - Fix csky_pmu.max_period assignment - Use generic free_initrd_mem() - entry: Remove unneeded need_resched() loop" * tag 'csky-for-linus-5.4-rc1' of git://github.com/c-sky/csky-linux: csky: Move static keyword to the front of declaration csky: entry: Remove unneeded need_resched() loop csky: Fixup csky_pmu.max_period assignment csky: Fixup add zero_fp fixup perf backtrace panic csky: Use generic free_initrd_mem() csky: Fixup 610 vipt cache flush mechanism csky: Support kernel non-aligned access csky: Fixup defer cache flush for 610 csky: Fixup arch_get_unmapped_area() implementation csky: Fixup ioremap function losing csky: Optimize arch_sync_dma_for_cpu/device with dma_inv_range csky/dma: Fixup cache_op failed when cross memory ZONEs csky: Fixup dma_alloc_coherent with PAGE_SO attribute csky: Fixup mb() synchronization problem
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git://git.kernel.org/pub/scm/linux/kernel/git/soc/socLinus Torvalds authored
Pull ARM SoC fixes from Olof Johansson: "A few fixes that have trickled in through the merge window: - Video fixes for OMAP due to panel-dpi driver removal - Clock fixes for OMAP that broke no-idle quirks + nfsroot on DRA7 - Fixing arch version on ASpeed ast2500 - Two fixes for reset handling on ARM SCMI" * tag 'armsoc-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc: ARM: aspeed: ast2500 is ARMv6K reset: reset-scmi: add missing handle initialisation firmware: arm_scmi: reset: fix reset_state assignment in scmi_domain_reset bus: ti-sysc: Remove unpaired sysc_clkdm_deny_idle() ARM: dts: logicpd-som-lv: Fix i2c2 and i2c3 Pin mux ARM: dts: am3517-evm: Fix missing video ARM: dts: logicpd-torpedo-baseboard: Fix missing video ARM: omap2plus_defconfig: Fix missing video bus: ti-sysc: Fix handling of invalid clocks bus: ti-sysc: Fix clock handling for no-idle quirks
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git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-traceLinus Torvalds authored
Pull tracing fixes from Steven Rostedt: "A few more tracing fixes: - Fix a buffer overflow by checking nr_args correctly in probes - Fix a warning that is reported by clang - Fix a possible memory leak in error path of filter processing - Fix the selftest that checks for failures, but wasn't failing - Minor clean up on call site output of a memory trace event" * tag 'trace-v5.4-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: selftests/ftrace: Fix same probe error test mm, tracing: Print symbol name for call_site in trace events tracing: Have error path in predicate_parse() free its allocated memory tracing: Fix clang -Wint-in-bool-context warnings in IF_ASSIGN macro tracing/probe: Fix to check the difference of nr_args before adding probe
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git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmcLinus Torvalds authored
Pull more MMC updates from Ulf Hansson: "A couple more updates/fixes for MMC: - sdhci-pci: Add Genesys Logic GL975x support - sdhci-tegra: Recover loss in throughput for DMA - sdhci-of-esdhc: Fix DMA bug" * tag 'mmc-v5.4-2' of git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc: mmc: host: sdhci-pci: Add Genesys Logic GL975x support mmc: tegra: Implement ->set_dma_mask() mmc: sdhci: Let drivers define their DMA mask mmc: sdhci-of-esdhc: set DMA snooping based on DMA coherence mmc: sdhci: improve ADMA error reporting
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Krzysztof Wilczynski authored
Move the static keyword to the front of declaration of csky_pmu_of_device_ids, and resolve the following compiler warning that can be seen when building with warnings enabled (W=1): arch/csky/kernel/perf_event.c:1340:1: warning: ‘static’ is not at beginning of declaration [-Wold-style-declaration] Signed-off-by: Krzysztof Wilczynski <kw@linux.com> Signed-off-by: Guo Ren <guoren@kernel.org>
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Valentin Schneider authored
Since the enabling and disabling of IRQs within preempt_schedule_irq() is contained in a need_resched() loop, we don't need the outer arch code loop. Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> Signed-off-by: Guo Ren <guoren@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-miscLinus Torvalds authored
Pull Documentation/process update from Greg KH: "Here are two small Documentation/process/embargoed-hardware-issues.rst file updates that missed my previous char/misc pull request. The first one adds an Intel representative for the process, and the second one cleans up the text a bit more when it comes to how the disclosure rules work, as it was a bit confusing to some companies" * tag 'char-misc-5.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: Documentation/process: Clarify disclosure rules Documentation/process: Volunteer as the ambassador for Intel
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git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfsLinus Torvalds authored
Pull more vfs updates from Al Viro: "A couple of misc patches" * 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: afs dynroot: switch to simple_dir_operations fs/handle.c - fix up kerneldoc
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git://git.samba.org/sfrench/cifs-2.6Linus Torvalds authored
Pull more cifs updates from Steve French: "Fixes from the recent SMB3 Test events and Storage Developer Conference (held the last two weeks). Here are nine smb3 patches including an important patch for debugging traces with wireshark, with three patches marked for stable. Additional fixes from last week to better handle some newly discovered reparse points, and a fix the create/mkdir path for setting the mode more atomically (in SMB3 Create security descriptor context), and one for path name processing are still being tested so are not included here" * tag '5.4-rc-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6: CIFS: Fix oplock handling for SMB 2.1+ protocols smb3: missing ACL related flags smb3: pass mode bits into create calls smb3: Add missing reparse tags CIFS: fix max ea value size fs/cifs/sess.c: Remove set but not used variable 'capabilities' fs/cifs/smb2pdu.c: Make SMB2_notify_init static smb3: fix leak in "open on server" perf counter smb3: allow decryption keys to be dumped by admin for debugging
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Mao Han authored
The csky_pmu.max_period has type u64, and BIT() can only return 32 bits unsigned long on C-SKY. The initialization for max_period will be incorrect when count_width is bigger than 32. Use BIT_ULL() Signed-off-by: Mao Han <han_mao@c-sky.com> Signed-off-by: Guo Ren <ren_guo@c-sky.com>
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Guo Ren authored
We need set fp zero to let backtrace know the end. The patch fixup perf callchain panic problem, because backtrace didn't know what is the end of fp. Signed-off-by: Guo Ren <ren_guo@c-sky.com> Reported-by: Mao Han <han_mao@c-sky.com>
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Mike Rapoport authored
The csky implementation of free_initrd_mem() is an open-coded version of free_reserved_area() without poisoning. Remove it and make csky use the generic version of free_initrd_mem(). Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Signed-off-by: Guo Ren <guoren@kernel.org>
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Linus Torvalds authored
Merge active entropy generation updates. This is admittedly partly "for discussion". We need to have a way forward for the boot time deadlocks where user space ends up waiting for more entropy, but no entropy is forthcoming because the system is entirely idle just waiting for something to happen. While this was triggered by what is arguably a user space bug with GDM/gnome-session asking for secure randomness during early boot, when they didn't even need any such truly secure thing, the issue ends up being that our "getrandom()" interface is prone to that kind of confusion, because people don't think very hard about whether they want to block for sufficient amounts of entropy. The approach here-in is to decide to not just passively wait for entropy to happen, but to start actively collecting it if it is missing. This is not necessarily always possible, but if the architecture has a CPU cycle counter, there is a fair amount of noise in the exact timings of reasonably complex loads. We may end up tweaking the load and the entropy estimates, but this should be at least a reasonable starting point. As part of this, we also revert the revert of the ext4 IO pattern improvement that ended up triggering the reported lack of external entropy. * getrandom() active entropy waiting: Revert "Revert "ext4: make __ext4_get_inode_loc plug"" random: try to actively add entropy rather than passively wait for it
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Linus Torvalds authored
This reverts commit 72dbcf72. Instead of waiting forever for entropy that may just not happen, we now try to actively generate entropy when required, and are thus hopefully avoiding the problem that caused the nice ext4 IO pattern fix to be reverted. So revert the revert. Cc: Ahmed S. Darwish <darwish.07@gmail.com> Cc: Ted Ts'o <tytso@mit.edu> Cc: Willy Tarreau <w@1wt.eu> Cc: Alexander E. Patrakov <patrakov@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Linus Torvalds authored
For 5.3 we had to revert a nice ext4 IO pattern improvement, because it caused a bootup regression due to lack of entropy at bootup together with arguably broken user space that was asking for secure random numbers when it really didn't need to. See commit 72dbcf72 (Revert "ext4: make __ext4_get_inode_loc plug"). This aims to solve the issue by actively generating entropy noise using the CPU cycle counter when waiting for the random number generator to initialize. This only works when you have a high-frequency time stamp counter available, but that's the case on all modern x86 CPU's, and on most other modern CPU's too. What we do is to generate jitter entropy from the CPU cycle counter under a somewhat complex load: calling the scheduler while also guaranteeing a certain amount of timing noise by also triggering a timer. I'm sure we can tweak this, and that people will want to look at other alternatives, but there's been a number of papers written on jitter entropy, and this should really be fairly conservative by crediting one bit of entropy for every timer-induced jump in the cycle counter. Not because the timer itself would be all that unpredictable, but because the interaction between the timer and the loop is going to be. Even if (and perhaps particularly if) the timer actually happens on another CPU, the cacheline interaction between the loop that reads the cycle counter and the timer itself firing is going to add perturbations to the cycle counter values that get mixed into the entropy pool. As Thomas pointed out, with a modern out-of-order CPU, even quite simple loops show a fair amount of hard-to-predict timing variability even in the absense of external interrupts. But this tries to take that further by actually having a fairly complex interaction. This is not going to solve the entropy issue for architectures that have no CPU cycle counter, but it's not clear how (and if) that is solvable, and the hardware in question is largely starting to be irrelevant. And by doing this we can at least avoid some of the even more contentious approaches (like making the entropy waiting time out in order to avoid the possibly unbounded waiting). Cc: Ahmed Darwish <darwish.07@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Theodore Ts'o <tytso@mit.edu> Cc: Nicholas Mc Guire <hofrat@opentech.at> Cc: Andy Lutomirski <luto@kernel.org> Cc: Kees Cook <keescook@chromium.org> Cc: Willy Tarreau <w@1wt.eu> Cc: Alexander E. Patrakov <patrakov@gmail.com> Cc: Lennart Poettering <mzxreary@0pointer.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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- 29 Sep, 2019 1 commit
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Olof Johansson authored
Merge tag 'fixes-5.4-merge-window' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap into arm/fixes Fixes for omap variants Few fixes for ti-sysc interconnect target module driver for no-idle quirks that caused nfsroot to fail on some dra7 boards. And let's fixes to get LCD working again for logicpd board that got broken a while back with removal of panel-dpi driver. We need to now use generic CONFIG_DRM_PANEL_SIMPLE instead. * tag 'fixes-5.4-merge-window' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap: bus: ti-sysc: Remove unpaired sysc_clkdm_deny_idle() ARM: dts: logicpd-som-lv: Fix i2c2 and i2c3 Pin mux ARM: dts: am3517-evm: Fix missing video ARM: dts: logicpd-torpedo-baseboard: Fix missing video ARM: omap2plus_defconfig: Fix missing video bus: ti-sysc: Fix handling of invalid clocks bus: ti-sysc: Fix clock handling for no-idle quirks Link: https://lore.kernel.org/r/pull-1568819401-72461@atomide.comSigned-off-by: Olof Johansson <olof@lixom.net>
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