From 5acba71e18833b9d06686b3751598bfa263a3ac3 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Thu, 24 Mar 2016 15:37:59 +0100 Subject: locking/atomic: Introduce atomic_fetch_or() This is deemed to replace the type generic fetch_or() which brings a lot of issues such as macro induced block variable aliasing and sloppy types. Not to mention fetch_or() doesn't refer to any namespace, adding even more confusion. So lets provide an atomic_t version. Current and next users of fetch_or() are thus encouraged to use atomic_t. Signed-off-by: Frederic Weisbecker Cc: Andrew Morton Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1458830281-4255-2-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar --- include/linux/atomic.h | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/include/linux/atomic.h b/include/linux/atomic.h index df4f369254c0..3d64c0852164 100644 --- a/include/linux/atomic.h +++ b/include/linux/atomic.h @@ -558,6 +558,27 @@ static inline int atomic_dec_if_positive(atomic_t *v) } #endif +/** + * atomic_fetch_or - perform *p |= mask and return old value of *p + * @p: pointer to atomic_t + * @mask: mask to OR on the atomic_t + */ +#ifndef atomic_fetch_or +static inline int atomic_fetch_or(atomic_t *p, int mask) +{ + int old, val = atomic_read(p); + + for (;;) { + old = atomic_cmpxchg(p, val, val | mask); + if (old == val) + break; + val = old; + } + + return old; +} +#endif + /** * fetch_or - perform *ptr |= mask and return old value of *ptr * @ptr: pointer to value -- cgit v1.2.3-58-ga151 From f009a7a767e792d5ab0b46c08d46236ea5271dd9 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Thu, 24 Mar 2016 15:38:00 +0100 Subject: timers/nohz: Convert tick dependency mask to atomic_t The tick dependency mask was intially unsigned long because this is the type on which clear_bit() operates on and fetch_or() accepts it. But now that we have atomic_fetch_or(), we can instead use atomic_andnot() to clear the bit. This consolidates the type of our tick dependency mask, reduce its size on structures and benefit from possible architecture optimizations on atomic_t operations. Suggested-by: Linus Torvalds Signed-off-by: Frederic Weisbecker Cc: Andrew Morton Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1458830281-4255-3-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar --- include/linux/sched.h | 4 ++-- kernel/time/tick-sched.c | 61 ++++++++++++++++++++++++------------------------ kernel/time/tick-sched.h | 2 +- 3 files changed, 33 insertions(+), 34 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 60bba7e032dc..52c4847b05e2 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -720,7 +720,7 @@ struct signal_struct { struct task_cputime cputime_expires; #ifdef CONFIG_NO_HZ_FULL - unsigned long tick_dep_mask; + atomic_t tick_dep_mask; #endif struct list_head cpu_timers[3]; @@ -1549,7 +1549,7 @@ struct task_struct { #endif #ifdef CONFIG_NO_HZ_FULL - unsigned long tick_dep_mask; + atomic_t tick_dep_mask; #endif unsigned long nvcsw, nivcsw; /* context switch counts */ u64 start_time; /* monotonic time in nsec */ diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 084b79f5917e..58e3310c9b21 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -157,52 +157,50 @@ static void tick_sched_handle(struct tick_sched *ts, struct pt_regs *regs) cpumask_var_t tick_nohz_full_mask; cpumask_var_t housekeeping_mask; bool tick_nohz_full_running; -static unsigned long tick_dep_mask; +static atomic_t tick_dep_mask; -static void trace_tick_dependency(unsigned long dep) +static bool check_tick_dependency(atomic_t *dep) { - if (dep & TICK_DEP_MASK_POSIX_TIMER) { + int val = atomic_read(dep); + + if (val & TICK_DEP_MASK_POSIX_TIMER) { trace_tick_stop(0, TICK_DEP_MASK_POSIX_TIMER); - return; + return true; } - if (dep & TICK_DEP_MASK_PERF_EVENTS) { + if (val & TICK_DEP_MASK_PERF_EVENTS) { trace_tick_stop(0, TICK_DEP_MASK_PERF_EVENTS); - return; + return true; } - if (dep & TICK_DEP_MASK_SCHED) { + if (val & TICK_DEP_MASK_SCHED) { trace_tick_stop(0, TICK_DEP_MASK_SCHED); - return; + return true; } - if (dep & TICK_DEP_MASK_CLOCK_UNSTABLE) + if (val & TICK_DEP_MASK_CLOCK_UNSTABLE) { trace_tick_stop(0, TICK_DEP_MASK_CLOCK_UNSTABLE); + return true; + } + + return false; } static bool can_stop_full_tick(struct tick_sched *ts) { WARN_ON_ONCE(!irqs_disabled()); - if (tick_dep_mask) { - trace_tick_dependency(tick_dep_mask); + if (check_tick_dependency(&tick_dep_mask)) return false; - } - if (ts->tick_dep_mask) { - trace_tick_dependency(ts->tick_dep_mask); + if (check_tick_dependency(&ts->tick_dep_mask)) return false; - } - if (current->tick_dep_mask) { - trace_tick_dependency(current->tick_dep_mask); + if (check_tick_dependency(¤t->tick_dep_mask)) return false; - } - if (current->signal->tick_dep_mask) { - trace_tick_dependency(current->signal->tick_dep_mask); + if (check_tick_dependency(¤t->signal->tick_dep_mask)) return false; - } return true; } @@ -259,12 +257,12 @@ static void tick_nohz_full_kick_all(void) preempt_enable(); } -static void tick_nohz_dep_set_all(unsigned long *dep, +static void tick_nohz_dep_set_all(atomic_t *dep, enum tick_dep_bits bit) { - unsigned long prev; + int prev; - prev = fetch_or(dep, BIT_MASK(bit)); + prev = atomic_fetch_or(dep, BIT(bit)); if (!prev) tick_nohz_full_kick_all(); } @@ -280,7 +278,7 @@ void tick_nohz_dep_set(enum tick_dep_bits bit) void tick_nohz_dep_clear(enum tick_dep_bits bit) { - clear_bit(bit, &tick_dep_mask); + atomic_andnot(BIT(bit), &tick_dep_mask); } /* @@ -289,12 +287,12 @@ void tick_nohz_dep_clear(enum tick_dep_bits bit) */ void tick_nohz_dep_set_cpu(int cpu, enum tick_dep_bits bit) { - unsigned long prev; + int prev; struct tick_sched *ts; ts = per_cpu_ptr(&tick_cpu_sched, cpu); - prev = fetch_or(&ts->tick_dep_mask, BIT_MASK(bit)); + prev = atomic_fetch_or(&ts->tick_dep_mask, BIT(bit)); if (!prev) { preempt_disable(); /* Perf needs local kick that is NMI safe */ @@ -313,7 +311,7 @@ void tick_nohz_dep_clear_cpu(int cpu, enum tick_dep_bits bit) { struct tick_sched *ts = per_cpu_ptr(&tick_cpu_sched, cpu); - clear_bit(bit, &ts->tick_dep_mask); + atomic_andnot(BIT(bit), &ts->tick_dep_mask); } /* @@ -331,7 +329,7 @@ void tick_nohz_dep_set_task(struct task_struct *tsk, enum tick_dep_bits bit) void tick_nohz_dep_clear_task(struct task_struct *tsk, enum tick_dep_bits bit) { - clear_bit(bit, &tsk->tick_dep_mask); + atomic_andnot(BIT(bit), &tsk->tick_dep_mask); } /* @@ -345,7 +343,7 @@ void tick_nohz_dep_set_signal(struct signal_struct *sig, enum tick_dep_bits bit) void tick_nohz_dep_clear_signal(struct signal_struct *sig, enum tick_dep_bits bit) { - clear_bit(bit, &sig->tick_dep_mask); + atomic_andnot(BIT(bit), &sig->tick_dep_mask); } /* @@ -366,7 +364,8 @@ void __tick_nohz_task_switch(void) ts = this_cpu_ptr(&tick_cpu_sched); if (ts->tick_stopped) { - if (current->tick_dep_mask || current->signal->tick_dep_mask) + if (atomic_read(¤t->tick_dep_mask) || + atomic_read(¤t->signal->tick_dep_mask)) tick_nohz_full_kick(); } out: diff --git a/kernel/time/tick-sched.h b/kernel/time/tick-sched.h index eb4e32566a83..bf38226e5c17 100644 --- a/kernel/time/tick-sched.h +++ b/kernel/time/tick-sched.h @@ -60,7 +60,7 @@ struct tick_sched { u64 next_timer; ktime_t idle_expires; int do_timer_last; - unsigned long tick_dep_mask; + atomic_t tick_dep_mask; }; extern struct tick_sched *tick_get_tick_sched(int cpu); -- cgit v1.2.3-58-ga151 From 5529578a27288d11d4d15635c258c6dde0f0fb10 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Thu, 24 Mar 2016 15:38:01 +0100 Subject: locking/atomic, sched: Unexport fetch_or() This patch functionally reverts: 5fd7a09cfb8c ("atomic: Export fetch_or()") During the merge Linus observed that the generic version of fetch_or() was messy: " This makes the ugly "fetch_or()" macro that the scheduler used internally a new generic helper, and does a bad job at it. " e23604edac2a Merge branch 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Now that we have introduced atomic_fetch_or(), fetch_or() is only used by the scheduler in order to deal with thread_info flags which type can vary across architectures. Lets confine fetch_or() back to the scheduler so that we encourage future users to use the more robust and well typed atomic_t version instead. While at it, fetch_or() gets robustified, pasting improvements from a previous patch by Ingo Molnar that avoids needless expression re-evaluations in the loop. Reported-by: Linus Torvalds Signed-off-by: Frederic Weisbecker Cc: Andrew Morton Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1458830281-4255-4-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar --- include/linux/atomic.h | 21 --------------------- kernel/sched/core.c | 18 ++++++++++++++++++ 2 files changed, 18 insertions(+), 21 deletions(-) diff --git a/include/linux/atomic.h b/include/linux/atomic.h index 3d64c0852164..506c3531832e 100644 --- a/include/linux/atomic.h +++ b/include/linux/atomic.h @@ -579,27 +579,6 @@ static inline int atomic_fetch_or(atomic_t *p, int mask) } #endif -/** - * fetch_or - perform *ptr |= mask and return old value of *ptr - * @ptr: pointer to value - * @mask: mask to OR on the value - * - * cmpxchg based fetch_or, macro so it works for different integer types - */ -#ifndef fetch_or -#define fetch_or(ptr, mask) \ -({ typeof(*(ptr)) __old, __val = *(ptr); \ - for (;;) { \ - __old = cmpxchg((ptr), __val, __val | (mask)); \ - if (__old == __val) \ - break; \ - __val = __old; \ - } \ - __old; \ -}) -#endif - - #ifdef CONFIG_GENERIC_ATOMIC64 #include #endif diff --git a/kernel/sched/core.c b/kernel/sched/core.c index d8465eeab8b3..8b489fcac37b 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -321,6 +321,24 @@ static inline void init_hrtick(void) } #endif /* CONFIG_SCHED_HRTICK */ +/* + * cmpxchg based fetch_or, macro so it works for different integer types + */ +#define fetch_or(ptr, mask) \ + ({ \ + typeof(ptr) _ptr = (ptr); \ + typeof(mask) _mask = (mask); \ + typeof(*_ptr) _old, _val = *_ptr; \ + \ + for (;;) { \ + _old = cmpxchg(_ptr, _val, _val | _mask); \ + if (_old == _val) \ + break; \ + _val = _old; \ + } \ + _old; \ +}) + #if defined(CONFIG_SMP) && defined(TIF_POLLING_NRFLAG) /* * Atomically set TIF_NEED_RESCHED and test for TIF_POLLING_NRFLAG, -- cgit v1.2.3-58-ga151 From a189c017ded0f13650793067fb7a1afbc2b98cd5 Mon Sep 17 00:00:00 2001 From: Sedat Dilek Date: Wed, 30 Mar 2016 10:22:49 +0200 Subject: tools/lib/lockdep: Fix unsupported 'basename -s' in run_tests.sh Here on Ubuntu/precise I have GNU/coreutils v8.13 installed where 'basename -s' is not supported. The result is that run_tests.sh is not done properly. How to reproduce: $ cd $BUILD_DIR $ LC_ALL=C make -C tools/ liblockdep $ cd tools/lib/lockdep/ $ LC_ALL=C ./run_tests.sh basename: invalid option -- 's' Try `basename --help' for more information. ... timeout: failed to run command `./tests/': Permission denied FAILED! rm: cannot remove `tests/': Is a directory Due to unsupported basename the tests programs are not generated and cannot be removed. Fix this by doing a compatible basename invocation and check for the existence of generated tests programs. For more details see this LKML thread: http://marc.info/?t=145906667300001&r=1&w=2 Signed-off-by: Sedat Dilek Cc: Boqun Feng Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Sasha Levin (maintainer:LIBLOCKDEP) Cc: Shuah Khan Cc: Theodore Ts'o Cc: Thomas Gleixner Cc: linux-fsdevel Link: http://lkml.kernel.org/r/1459326169-7009-1-git-send-email-sedat.dilek@gmail.com Signed-off-by: Ingo Molnar --- tools/lib/lockdep/run_tests.sh | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/tools/lib/lockdep/run_tests.sh b/tools/lib/lockdep/run_tests.sh index 5334ad9d39b7..1069d96248c1 100755 --- a/tools/lib/lockdep/run_tests.sh +++ b/tools/lib/lockdep/run_tests.sh @@ -3,7 +3,7 @@ make &> /dev/null for i in `ls tests/*.c`; do - testname=$(basename -s .c "$i") + testname=$(basename "$i" .c) gcc -o tests/$testname -pthread -lpthread $i liblockdep.a -Iinclude -D__USE_LIBLOCKDEP &> /dev/null echo -ne "$testname... " if [ $(timeout 1 ./tests/$testname | wc -l) -gt 0 ]; then @@ -11,11 +11,13 @@ for i in `ls tests/*.c`; do else echo "FAILED!" fi - rm tests/$testname + if [ -f "tests/$testname" ]; then + rm tests/$testname + fi done for i in `ls tests/*.c`; do - testname=$(basename -s .c "$i") + testname=$(basename "$i" .c) gcc -o tests/$testname -pthread -lpthread -Iinclude $i &> /dev/null echo -ne "(PRELOAD) $testname... " if [ $(timeout 1 ./lockdep ./tests/$testname | wc -l) -gt 0 ]; then @@ -23,5 +25,7 @@ for i in `ls tests/*.c`; do else echo "FAILED!" fi - rm tests/$testname + if [ -f "tests/$testname" ]; then + rm tests/$testname + fi done -- cgit v1.2.3-58-ga151 From 283d757378371e8044d873e661b1dccee46c5887 Mon Sep 17 00:00:00 2001 From: Denys Vlasenko Date: Wed, 30 Mar 2016 00:14:57 +0200 Subject: uapi/linux/stddef.h: Provide __always_inline to userspace headers Josh Boyer reported that my recent change to uapi/linux/swab.h broke the Qemu build: bc27fb68aaad ("include/uapi/linux/byteorder, swab: force inlining of some byteswap operations") Unfortunately, UAPI headers don't include compiler.h so fixing it there is not enough, add an __always_inline definition to uapi/linux/stddef.h instead. Testcase: "make headers_install" and try to compile this: #include void main() {} Reported-by: Josh Boyer Signed-off-by: Denys Vlasenko Cc: Andrew Morton Cc: Arnd Bergmann Cc: David Rientjes Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Thomas Graf Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/1459289697-12875-1-git-send-email-dvlasenk@redhat.com Signed-off-by: Ingo Molnar --- include/uapi/linux/stddef.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/include/uapi/linux/stddef.h b/include/uapi/linux/stddef.h index aa9f10428743..621fa8ac4425 100644 --- a/include/uapi/linux/stddef.h +++ b/include/uapi/linux/stddef.h @@ -1 +1,5 @@ #include + +#ifndef __always_inline +#define __always_inline inline +#endif -- cgit v1.2.3-58-ga151 From 39e2e173fb1f900959d3a25c21c65fa88b06c6ee Mon Sep 17 00:00:00 2001 From: Alfredo Alvarez Fernandez Date: Wed, 30 Mar 2016 19:03:36 +0200 Subject: locking/lockdep: Print chain_key collision information A sequence of pairs [class_idx -> corresponding chain_key iteration] is printed for both the current held_lock chain and the cached chain. That exposes the two different class_idx sequences that led to that particular hash value. This helps with debugging hash chain collision reports. Signed-off-by: Alfredo Alvarez Fernandez Acked-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-fsdevel@vger.kernel.org Cc: sedat.dilek@gmail.com Cc: tytso@mit.edu Link: http://lkml.kernel.org/r/1459357416-19190-1-git-send-email-alfredoalvarezernandez@gmail.com Signed-off-by: Ingo Molnar --- kernel/locking/lockdep.c | 79 ++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 77 insertions(+), 2 deletions(-) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 53ab2f85d77e..2324ba5310db 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -1999,6 +1999,77 @@ static inline int get_first_held_lock(struct task_struct *curr, return ++i; } +/* + * Returns the next chain_key iteration + */ +static u64 print_chain_key_iteration(int class_idx, u64 chain_key) +{ + u64 new_chain_key = iterate_chain_key(chain_key, class_idx); + + printk(" class_idx:%d -> chain_key:%016Lx", + class_idx, + (unsigned long long)new_chain_key); + return new_chain_key; +} + +static void +print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next) +{ + struct held_lock *hlock; + u64 chain_key = 0; + int depth = curr->lockdep_depth; + int i; + + printk("depth: %u\n", depth + 1); + for (i = get_first_held_lock(curr, hlock_next); i < depth; i++) { + hlock = curr->held_locks + i; + chain_key = print_chain_key_iteration(hlock->class_idx, chain_key); + + print_lock(hlock); + } + + print_chain_key_iteration(hlock_next->class_idx, chain_key); + print_lock(hlock_next); +} + +static void print_chain_keys_chain(struct lock_chain *chain) +{ + int i; + u64 chain_key = 0; + int class_id; + + printk("depth: %u\n", chain->depth); + for (i = 0; i < chain->depth; i++) { + class_id = chain_hlocks[chain->base + i]; + chain_key = print_chain_key_iteration(class_id + 1, chain_key); + + print_lock_name(lock_classes + class_id); + printk("\n"); + } +} + +static void print_collision(struct task_struct *curr, + struct held_lock *hlock_next, + struct lock_chain *chain) +{ + printk("\n"); + printk("======================\n"); + printk("[chain_key collision ]\n"); + print_kernel_ident(); + printk("----------------------\n"); + printk("%s/%d: ", current->comm, task_pid_nr(current)); + printk("Hash chain already cached but the contents don't match!\n"); + + printk("Held locks:"); + print_chain_keys_held_locks(curr, hlock_next); + + printk("Locks in cached chain:"); + print_chain_keys_chain(chain); + + printk("\nstack backtrace:\n"); + dump_stack(); +} + /* * Checks whether the chain and the current held locks are consistent * in depth and also in content. If they are not it most likely means @@ -2014,14 +2085,18 @@ static int check_no_collision(struct task_struct *curr, i = get_first_held_lock(curr, hlock); - if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) + if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) { + print_collision(curr, hlock, chain); return 0; + } for (j = 0; j < chain->depth - 1; j++, i++) { id = curr->held_locks[i].class_idx - 1; - if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) + if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) { + print_collision(curr, hlock, chain); return 0; + } } #endif return 1; -- cgit v1.2.3-58-ga151 From 353def94606fda16d9ae1761b4b0583286481ec5 Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Thu, 31 Mar 2016 22:33:23 +0900 Subject: MAINTAINERS: Update my email address Since I moved to Linaro, this old address doesn't work anymore. I'll use my kernel.org account for upstreaming. Signed-off-by: Masami Hiramatsu Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: acme@redhat.com Cc: rostedt@goodmis.org Link: http://lkml.kernel.org/r/1459431203-7438-1-git-send-email-mhiramat@kernel.org Signed-off-by: Ingo Molnar --- MAINTAINERS | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/MAINTAINERS b/MAINTAINERS index 378ebfff2d1f..ed121a5b9319 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -6402,7 +6402,7 @@ KPROBES M: Ananth N Mavinakayanahalli M: Anil S Keshavamurthy M: "David S. Miller" -M: Masami Hiramatsu +M: Masami Hiramatsu S: Maintained F: Documentation/kprobes.txt F: include/linux/kprobes.h -- cgit v1.2.3-58-ga151