https://github.com/torvalds/linux
Revision 093e5840ae76f1082633503964d035f40ed0216d authored by Sebastian Andrzej Siewior on 21 December 2015, 17:17:10 UTC, committed by Ingo Molnar on 06 January 2016, 10:01:07 UTC
In the following commit:
7675104990ed ("sched: Implement lockless wake-queues")
we gained lockless wake-queues.
The -RT kernel managed to lockup itself with those. There could be multiple
attempts for task X to enqueue it for a wakeup _even_ if task X is already
running.
The reason is that task X could be runnable but not yet on CPU. The the
task performing the wakeup did not leave the CPU it could performe
multiple wakeups.
With the proper timming task X could be running and enqueued for a
wakeup. If this happens while X is performing a fork() then its its
child will have a !NULL `wake_q` member copied.
This is not a problem as long as the child task does not participate in
lockless wakeups :)
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 7675104990ed ("sched: Implement lockless wake-queues")
Link: http://lkml.kernel.org/r/20151221171710.GA5499@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
1 parent be958bd
Tip revision: 093e5840ae76f1082633503964d035f40ed0216d authored by Sebastian Andrzej Siewior on 21 December 2015, 17:17:10 UTC
sched/core: Reset task's lockless wake-queues on fork()
sched/core: Reset task's lockless wake-queues on fork()
Tip revision: 093e584
jedec_ddr_data.c
/*
* DDR addressing details and AC timing parameters from JEDEC specs
*
* Copyright (C) 2012 Texas Instruments, Inc.
*
* Aneesh V <aneesh@ti.com>
*
* 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.
*/
#include <memory/jedec_ddr.h>
#include <linux/module.h>
/* LPDDR2 addressing details from JESD209-2 section 2.4 */
const struct lpddr2_addressing
lpddr2_jedec_addressing_table[NUM_DDR_ADDR_TABLE_ENTRIES] = {
{B4, T_REFI_15_6, T_RFC_90}, /* 64M */
{B4, T_REFI_15_6, T_RFC_90}, /* 128M */
{B4, T_REFI_7_8, T_RFC_90}, /* 256M */
{B4, T_REFI_7_8, T_RFC_90}, /* 512M */
{B8, T_REFI_7_8, T_RFC_130}, /* 1GS4 */
{B8, T_REFI_3_9, T_RFC_130}, /* 2GS4 */
{B8, T_REFI_3_9, T_RFC_130}, /* 4G */
{B8, T_REFI_3_9, T_RFC_210}, /* 8G */
{B4, T_REFI_7_8, T_RFC_130}, /* 1GS2 */
{B4, T_REFI_3_9, T_RFC_130}, /* 2GS2 */
};
EXPORT_SYMBOL_GPL(lpddr2_jedec_addressing_table);
/* LPDDR2 AC timing parameters from JESD209-2 section 12 */
const struct lpddr2_timings
lpddr2_jedec_timings[NUM_DDR_TIMING_TABLE_ENTRIES] = {
/* Speed bin 400(200 MHz) */
[0] = {
.max_freq = 200000000,
.min_freq = 10000000,
.tRPab = 21000,
.tRCD = 18000,
.tWR = 15000,
.tRAS_min = 42000,
.tRRD = 10000,
.tWTR = 10000,
.tXP = 7500,
.tRTP = 7500,
.tCKESR = 15000,
.tDQSCK_max = 5500,
.tFAW = 50000,
.tZQCS = 90000,
.tZQCL = 360000,
.tZQinit = 1000000,
.tRAS_max_ns = 70000,
.tDQSCK_max_derated = 6000,
},
/* Speed bin 533(266 MHz) */
[1] = {
.max_freq = 266666666,
.min_freq = 10000000,
.tRPab = 21000,
.tRCD = 18000,
.tWR = 15000,
.tRAS_min = 42000,
.tRRD = 10000,
.tWTR = 7500,
.tXP = 7500,
.tRTP = 7500,
.tCKESR = 15000,
.tDQSCK_max = 5500,
.tFAW = 50000,
.tZQCS = 90000,
.tZQCL = 360000,
.tZQinit = 1000000,
.tRAS_max_ns = 70000,
.tDQSCK_max_derated = 6000,
},
/* Speed bin 800(400 MHz) */
[2] = {
.max_freq = 400000000,
.min_freq = 10000000,
.tRPab = 21000,
.tRCD = 18000,
.tWR = 15000,
.tRAS_min = 42000,
.tRRD = 10000,
.tWTR = 7500,
.tXP = 7500,
.tRTP = 7500,
.tCKESR = 15000,
.tDQSCK_max = 5500,
.tFAW = 50000,
.tZQCS = 90000,
.tZQCL = 360000,
.tZQinit = 1000000,
.tRAS_max_ns = 70000,
.tDQSCK_max_derated = 6000,
},
/* Speed bin 1066(533 MHz) */
[3] = {
.max_freq = 533333333,
.min_freq = 10000000,
.tRPab = 21000,
.tRCD = 18000,
.tWR = 15000,
.tRAS_min = 42000,
.tRRD = 10000,
.tWTR = 7500,
.tXP = 7500,
.tRTP = 7500,
.tCKESR = 15000,
.tDQSCK_max = 5500,
.tFAW = 50000,
.tZQCS = 90000,
.tZQCL = 360000,
.tZQinit = 1000000,
.tRAS_max_ns = 70000,
.tDQSCK_max_derated = 5620,
},
};
EXPORT_SYMBOL_GPL(lpddr2_jedec_timings);
const struct lpddr2_min_tck lpddr2_jedec_min_tck = {
.tRPab = 3,
.tRCD = 3,
.tWR = 3,
.tRASmin = 3,
.tRRD = 2,
.tWTR = 2,
.tXP = 2,
.tRTP = 2,
.tCKE = 3,
.tCKESR = 3,
.tFAW = 8
};
EXPORT_SYMBOL_GPL(lpddr2_jedec_min_tck);
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