/* * Copyright (C) 2012 ARM Ltd. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see . */ #ifndef __CLKSOURCE_ARM_ARCH_TIMER_H #define __CLKSOURCE_ARM_ARCH_TIMER_H #include #include #define ARCH_TIMER_CTRL_ENABLE (1 << 0) #define ARCH_TIMER_CTRL_IT_MASK (1 << 1) #define ARCH_TIMER_CTRL_IT_STAT (1 << 2) #define CNTHCTL_EL1PCTEN (1 << 0) #define CNTHCTL_EL1PCEN (1 << 1) #define CNTHCTL_EVNTEN (1 << 2) #define CNTHCTL_EVNTDIR (1 << 3) #define CNTHCTL_EVNTI (0xF << 4) enum arch_timer_reg { ARCH_TIMER_REG_CTRL, ARCH_TIMER_REG_TVAL, }; #define ARCH_TIMER_PHYS_ACCESS 0 #define ARCH_TIMER_VIRT_ACCESS 1 #define ARCH_TIMER_MEM_PHYS_ACCESS 2 #define ARCH_TIMER_MEM_VIRT_ACCESS 3 #define ARCH_TIMER_USR_PCT_ACCESS_EN (1 << 0) /* physical counter */ #define ARCH_TIMER_USR_VCT_ACCESS_EN (1 << 1) /* virtual counter */ #define ARCH_TIMER_VIRT_EVT_EN (1 << 2) #define ARCH_TIMER_EVT_TRIGGER_SHIFT (4) #define ARCH_TIMER_EVT_TRIGGER_MASK (0xF << ARCH_TIMER_EVT_TRIGGER_SHIFT) #define ARCH_TIMER_USR_VT_ACCESS_EN (1 << 8) /* virtual timer registers */ #define ARCH_TIMER_USR_PT_ACCESS_EN (1 << 9) /* physical timer registers */ #define ARCH_TIMER_EVT_STREAM_FREQ 10000 /* 100us */ struct arch_timer_kvm_info { struct timecounter timecounter; int virtual_irq; }; #ifdef CONFIG_ARM_ARCH_TIMER extern u32 arch_timer_get_rate(void); extern u64 (*arch_timer_read_counter)(void); extern struct arch_timer_kvm_info *arch_timer_get_kvm_info(void); #else static inline u32 arch_timer_get_rate(void) { return 0; } static inline u64 arch_timer_read_counter(void) { return 0; } #endif #endif >
path: root/sound/pci/hda/hda_intel.c
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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2017-01-10 02:28:26 -0800
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2017-01-14 21:23:48 -0800
commit52d7e48b86fc108e45a656d8e53e4237993c481d (patch)
tree5e95c29eb7a49a5c026e8f4af0c6b9da46f52122 /sound/pci/hda/hda_intel.c
parentf466ae66fa6a599f9a53b5f9bafea4b8cfffa7fb (diff)
rcu: Narrow early boot window of illegal synchronous grace periods
The current preemptible RCU implementation goes through three phases during bootup. In the first phase, there is only one CPU that is running with preemption disabled, so that a no-op is a synchronous grace period. In the second mid-boot phase, the scheduler is running, but RCU has not yet gotten its kthreads spawned (and, for expedited grace periods, workqueues are not yet running. During this time, any attempt to do a synchronous grace period will hang the system (or complain bitterly, depending). In the third and final phase, RCU is fully operational and everything works normally. This has been OK for some time, but there has recently been some synchronous grace periods showing up during the second mid-boot phase. This code worked "by accident" for awhile, but started failing as soon as expedited RCU grace periods switched over to workqueues in commit 8b355e3bc140 ("rcu: Drive expedited grace periods from workqueue"). Note that the code was buggy even before this commit, as it was subject to failure on real-time systems that forced all expedited grace periods to run as normal grace periods (for example, using the rcu_normal ksysfs parameter). The callchain from the failure case is as follows: early_amd_iommu_init() |-> acpi_put_table(ivrs_base); |-> acpi_tb_put_table(table_desc); |-> acpi_tb_invalidate_table(table_desc); |-> acpi_tb_release_table(...) |-> acpi_os_unmap_memory |-> acpi_os_unmap_iomem |-> acpi_os_map_cleanup |-> synchronize_rcu_expedited The kernel showing this callchain was built with CONFIG_PREEMPT_RCU=y, which caused the code to try using workqueues before they were initialized, which did not go well. This commit therefore reworks RCU to permit synchronous grace periods to proceed during this mid-boot phase. This commit is therefore a fix to a regression introduced in v4.9, and is therefore being put forward post-merge-window in v4.10. This commit sets a flag from the existing rcu_scheduler_starting() function which causes all synchronous grace periods to take the expedited path. The expedited path now checks this flag, using the requesting task to drive the expedited grace period forward during the mid-boot phase. Finally, this flag is updated by a core_initcall() function named rcu_exp_runtime_mode(), which causes the runtime codepaths to be used. Note that this arrangement assumes that tasks are not sent POSIX signals (or anything similar) from the time that the first task is spawned through core_initcall() time. Fixes: 8b355e3bc140 ("rcu: Drive expedited grace periods from workqueue") Reported-by: "Zheng, Lv" <lv.zheng@intel.com> Reported-by: Borislav Petkov <bp@alien8.de> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Tested-by: Stan Kain <stan.kain@gmail.com> Tested-by: Ivan <waffolz@hotmail.com> Tested-by: Emanuel Castelo <emanuel.castelo@gmail.com> Tested-by: Bruno Pesavento <bpesavento@infinito.it> Tested-by: Borislav Petkov <bp@suse.de> Tested-by: Frederic Bezies <fredbezies@gmail.com> Cc: <stable@vger.kernel.org> # 4.9.0-
Diffstat (limited to 'sound/pci/hda/hda_intel.c')