From 4446a36ff8c74ac3b32feb009b651048e129c6af Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Mon, 12 May 2008 21:21:05 +0200 Subject: rcu: add call_rcu_sched() Fourth cut of patch to provide the call_rcu_sched(). This is again to synchronize_sched() as call_rcu() is to synchronize_rcu(). Should be fine for experimental and -rt use, but not ready for inclusion. With some luck, I will be able to tell Andrew to come out of hiding on the next round. Passes multi-day rcutorture sessions with concurrent CPU hotplugging. Fixes since the first version include a bug that could result in indefinite blocking (spotted by Gautham Shenoy), better resiliency against CPU-hotplug operations, and other minor fixes. Fixes since the second version include reworking grace-period detection to avoid deadlocks that could happen when running concurrently with CPU hotplug, adding Mathieu's fix to avoid the softlockup messages, as well as Mathieu's fix to allow use earlier in boot. Fixes since the third version include a wrong-CPU bug spotted by Andrew, getting rid of the obsolete synchronize_kernel API that somehow snuck back in, merging spin_unlock() and local_irq_restore() in a few places, commenting the code that checks for quiescent states based on interrupting from user-mode execution or the idle loop, removing some inline attributes, and some code-style changes. Known/suspected shortcomings: o I still do not entirely trust the sleep/wakeup logic. Next step will be to use a private snapshot of the CPU online mask in rcu_sched_grace_period() -- if the CPU wasn't there at the start of the grace period, we don't need to hear from it. And the bit about accounting for changes in online CPUs inside of rcu_sched_grace_period() is ugly anyway. o It might be good for rcu_sched_grace_period() to invoke resched_cpu() when a given CPU wasn't responding quickly, but resched_cpu() is declared static... This patch also fixes a long-standing bug in the earlier preemptable-RCU implementation of synchronize_rcu() that could result in loss of concurrent external changes to a task's CPU affinity mask. I still cannot remember who reported this... Signed-off-by: Paul E. McKenney Signed-off-by: Mathieu Desnoyers Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- init/main.c | 1 + 1 file changed, 1 insertion(+) (limited to 'init') diff --git a/init/main.c b/init/main.c index f7fb20021d48..a9cc3e0803de 100644 --- a/init/main.c +++ b/init/main.c @@ -758,6 +758,7 @@ static void __init do_initcalls(void) */ static void __init do_basic_setup(void) { + rcu_init_sched(); /* needed by module_init stage. */ /* drivers will send hotplug events */ init_workqueues(); usermodehelper_init(); -- cgit v1.2.3-59-g8ed1b From 3da757daf86e498872855f0b5e101f763ba79499 Mon Sep 17 00:00:00 2001 From: Alok Kataria Date: Fri, 20 Jun 2008 15:06:33 -0700 Subject: x86: use cpu_khz for loops_per_jiffy calculation On the x86 platform we can use the value of tsc_khz computed during tsc calibration to calculate the loops_per_jiffy value. Its very important to keep the error in lpj values to minimum as any error in that may result in kernel panic in check_timer. In virtualization environment, On a highly overloaded host the guest delay calibration may sometimes result in errors beyond the ~50% that timer_irq_works can handle, resulting in the guest panicking. Does some formating changes to lpj_setup code to now have a single printk to print the bogomips value. We do this only for the boot processor because the AP's can have different base frequencies or the BIOS might boot a AP at a different frequency. Signed-off-by: Alok N Kataria Cc: Arjan van de Ven Cc: Daniel Hecht Cc: Tim Mann Cc: Zach Amsden Cc: Sahil Rihan Signed-off-by: Ingo Molnar --- arch/x86/kernel/time_64.c | 2 ++ arch/x86/kernel/tsc_32.c | 5 +++++ include/linux/delay.h | 1 + init/calibrate.c | 36 +++++++++++++++++++----------------- 4 files changed, 27 insertions(+), 17 deletions(-) (limited to 'init') diff --git a/arch/x86/kernel/time_64.c b/arch/x86/kernel/time_64.c index c737849e2ef7..12b4a71bd074 100644 --- a/arch/x86/kernel/time_64.c +++ b/arch/x86/kernel/time_64.c @@ -123,6 +123,8 @@ void __init time_init(void) (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)) cpu_khz = calculate_cpu_khz(); + lpj_tsc = ((unsigned long)tsc_khz * 1000)/HZ; + if (unsynchronized_tsc()) mark_tsc_unstable("TSCs unsynchronized"); diff --git a/arch/x86/kernel/tsc_32.c b/arch/x86/kernel/tsc_32.c index 068759db63dd..be729035b30b 100644 --- a/arch/x86/kernel/tsc_32.c +++ b/arch/x86/kernel/tsc_32.c @@ -401,6 +401,7 @@ static inline void check_geode_tsc_reliable(void) { } void __init tsc_init(void) { int cpu; + u64 lpj; if (!cpu_has_tsc || tsc_disabled) { /* Disable the TSC in case of !cpu_has_tsc */ @@ -421,6 +422,10 @@ void __init tsc_init(void) return; } + lpj = ((u64)tsc_khz * 1000); + do_div(lpj, HZ); + lpj_tsc = lpj; + printk("Detected %lu.%03lu MHz processor.\n", (unsigned long)cpu_khz / 1000, (unsigned long)cpu_khz % 1000); diff --git a/include/linux/delay.h b/include/linux/delay.h index 54552d21296e..01aec60590ab 100644 --- a/include/linux/delay.h +++ b/include/linux/delay.h @@ -41,6 +41,7 @@ static inline void ndelay(unsigned long x) #define ndelay(x) ndelay(x) #endif +extern unsigned long lpj_tsc; void calibrate_delay(void); void msleep(unsigned int msecs); unsigned long msleep_interruptible(unsigned int msecs); diff --git a/init/calibrate.c b/init/calibrate.c index ecb3822d4f70..86286974dada 100644 --- a/init/calibrate.c +++ b/init/calibrate.c @@ -8,7 +8,9 @@ #include #include #include +#include +unsigned long lpj_tsc; unsigned long preset_lpj; static int __init lpj_setup(char *str) { @@ -108,6 +110,10 @@ static unsigned long __cpuinit calibrate_delay_direct(void) {return 0;} * This is the number of bits of precision for the loops_per_jiffy. Each * bit takes on average 1.5/HZ seconds. This (like the original) is a little * better than 1% + * For the boot cpu we can skip the delay calibration and assign it a value + * calculated based on the tsc frequency. + * For the rest of the CPUs we cannot assume that the tsc frequency is same as + * the cpu frequency, hence do the calibration for those. */ #define LPS_PREC 8 @@ -118,20 +124,20 @@ void __cpuinit calibrate_delay(void) if (preset_lpj) { loops_per_jiffy = preset_lpj; - printk("Calibrating delay loop (skipped)... " - "%lu.%02lu BogoMIPS preset\n", - loops_per_jiffy/(500000/HZ), - (loops_per_jiffy/(5000/HZ)) % 100); + printk(KERN_INFO + "Calibrating delay loop (skipped) preset value.. "); + } else if ((smp_processor_id() == 0) && lpj_tsc) { + loops_per_jiffy = lpj_tsc; + printk(KERN_INFO + "Calibrating delay loop (skipped), " + "using tsc calculated value.. "); } else if ((loops_per_jiffy = calibrate_delay_direct()) != 0) { - printk("Calibrating delay using timer specific routine.. "); - printk("%lu.%02lu BogoMIPS (lpj=%lu)\n", - loops_per_jiffy/(500000/HZ), - (loops_per_jiffy/(5000/HZ)) % 100, - loops_per_jiffy); + printk(KERN_INFO + "Calibrating delay using timer specific routine.. "); } else { loops_per_jiffy = (1<<12); - printk(KERN_DEBUG "Calibrating delay loop... "); + printk(KERN_INFO "Calibrating delay loop... "); while ((loops_per_jiffy <<= 1) != 0) { /* wait for "start of" clock tick */ ticks = jiffies; @@ -161,12 +167,8 @@ void __cpuinit calibrate_delay(void) if (jiffies != ticks) /* longer than 1 tick */ loops_per_jiffy &= ~loopbit; } - - /* Round the value and print it */ - printk("%lu.%02lu BogoMIPS (lpj=%lu)\n", - loops_per_jiffy/(500000/HZ), - (loops_per_jiffy/(5000/HZ)) % 100, - loops_per_jiffy); } - + printk(KERN_INFO "%lu.%02lu BogoMIPS (lpj=%lu)\n", + loops_per_jiffy/(500000/HZ), + (loops_per_jiffy/(5000/HZ)) % 100, loops_per_jiffy); } -- cgit v1.2.3-59-g8ed1b From f3f3149f35b9195ef4b761b1353fc0766b5f53be Mon Sep 17 00:00:00 2001 From: Alok Kataria Date: Mon, 23 Jun 2008 18:21:56 -0700 Subject: x86: use cpu_khz for loops_per_jiffy calculation, cleanup As suggested by Ingo, remove all references to tsc from init/calibrate.c TSC is x86 specific, and using tsc in variable names in a generic file should be avoided. lpj_tsc is now called lpj_fine, since it is related to fine tuning of lpj value. Also tsc_rate_* is called timer_rate_* Signed-off-by: Alok N Kataria Cc: Arjan van de Ven Cc: Daniel Hecht Cc: Tim Mann Cc: Zach Amsden Cc: Sahil Rihan Signed-off-by: Ingo Molnar --- arch/x86/kernel/time_64.c | 2 +- arch/x86/kernel/tsc_32.c | 2 +- include/linux/delay.h | 2 +- init/calibrate.c | 36 +++++++++++++++++++----------------- 4 files changed, 22 insertions(+), 20 deletions(-) (limited to 'init') diff --git a/arch/x86/kernel/time_64.c b/arch/x86/kernel/time_64.c index 12b4a71bd074..39ae8511a137 100644 --- a/arch/x86/kernel/time_64.c +++ b/arch/x86/kernel/time_64.c @@ -123,7 +123,7 @@ void __init time_init(void) (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)) cpu_khz = calculate_cpu_khz(); - lpj_tsc = ((unsigned long)tsc_khz * 1000)/HZ; + lpj_fine = ((unsigned long)tsc_khz * 1000)/HZ; if (unsynchronized_tsc()) mark_tsc_unstable("TSCs unsynchronized"); diff --git a/arch/x86/kernel/tsc_32.c b/arch/x86/kernel/tsc_32.c index 0af49fb533e1..048baab77268 100644 --- a/arch/x86/kernel/tsc_32.c +++ b/arch/x86/kernel/tsc_32.c @@ -425,7 +425,7 @@ void __init tsc_init(void) lpj = ((u64)tsc_khz * 1000); do_div(lpj, HZ); - lpj_tsc = lpj; + lpj_fine = lpj; printk("Detected %lu.%03lu MHz processor.\n", (unsigned long)cpu_khz / 1000, diff --git a/include/linux/delay.h b/include/linux/delay.h index 01aec60590ab..fd832c6d419e 100644 --- a/include/linux/delay.h +++ b/include/linux/delay.h @@ -41,7 +41,7 @@ static inline void ndelay(unsigned long x) #define ndelay(x) ndelay(x) #endif -extern unsigned long lpj_tsc; +extern unsigned long lpj_fine; void calibrate_delay(void); void msleep(unsigned int msecs); unsigned long msleep_interruptible(unsigned int msecs); diff --git a/init/calibrate.c b/init/calibrate.c index 86286974dada..7963e3fc51d9 100644 --- a/init/calibrate.c +++ b/init/calibrate.c @@ -10,7 +10,7 @@ #include #include -unsigned long lpj_tsc; +unsigned long lpj_fine; unsigned long preset_lpj; static int __init lpj_setup(char *str) { @@ -35,9 +35,9 @@ static unsigned long __cpuinit calibrate_delay_direct(void) unsigned long pre_start, start, post_start; unsigned long pre_end, end, post_end; unsigned long start_jiffies; - unsigned long tsc_rate_min, tsc_rate_max; - unsigned long good_tsc_sum = 0; - unsigned long good_tsc_count = 0; + unsigned long timer_rate_min, timer_rate_max; + unsigned long good_timer_sum = 0; + unsigned long good_timer_count = 0; int i; if (read_current_timer(&pre_start) < 0 ) @@ -81,22 +81,24 @@ static unsigned long __cpuinit calibrate_delay_direct(void) } read_current_timer(&post_end); - tsc_rate_max = (post_end - pre_start) / DELAY_CALIBRATION_TICKS; - tsc_rate_min = (pre_end - post_start) / DELAY_CALIBRATION_TICKS; + timer_rate_max = (post_end - pre_start) / + DELAY_CALIBRATION_TICKS; + timer_rate_min = (pre_end - post_start) / + DELAY_CALIBRATION_TICKS; /* - * If the upper limit and lower limit of the tsc_rate is + * If the upper limit and lower limit of the timer_rate is * >= 12.5% apart, redo calibration. */ if (pre_start != 0 && pre_end != 0 && - (tsc_rate_max - tsc_rate_min) < (tsc_rate_max >> 3)) { - good_tsc_count++; - good_tsc_sum += tsc_rate_max; + (timer_rate_max - timer_rate_min) < (timer_rate_max >> 3)) { + good_timer_count++; + good_timer_sum += timer_rate_max; } } - if (good_tsc_count) - return (good_tsc_sum/good_tsc_count); + if (good_timer_count) + return (good_timer_sum/good_timer_count); printk(KERN_WARNING "calibrate_delay_direct() failed to get a good " "estimate for loops_per_jiffy.\nProbably due to long platform interrupts. Consider using \"lpj=\" boot option.\n"); @@ -111,8 +113,8 @@ static unsigned long __cpuinit calibrate_delay_direct(void) {return 0;} * bit takes on average 1.5/HZ seconds. This (like the original) is a little * better than 1% * For the boot cpu we can skip the delay calibration and assign it a value - * calculated based on the tsc frequency. - * For the rest of the CPUs we cannot assume that the tsc frequency is same as + * calculated based on the timer frequency. + * For the rest of the CPUs we cannot assume that the timer frequency is same as * the cpu frequency, hence do the calibration for those. */ #define LPS_PREC 8 @@ -126,11 +128,11 @@ void __cpuinit calibrate_delay(void) loops_per_jiffy = preset_lpj; printk(KERN_INFO "Calibrating delay loop (skipped) preset value.. "); - } else if ((smp_processor_id() == 0) && lpj_tsc) { - loops_per_jiffy = lpj_tsc; + } else if ((smp_processor_id() == 0) && lpj_fine) { + loops_per_jiffy = lpj_fine; printk(KERN_INFO "Calibrating delay loop (skipped), " - "using tsc calculated value.. "); + "value calculated using timer frequency.. "); } else if ((loops_per_jiffy = calibrate_delay_direct()) != 0) { printk(KERN_INFO "Calibrating delay using timer specific routine.. "); -- cgit v1.2.3-59-g8ed1b From 3d4422332711ef48ef0f132f1fcbfcbd56c7f3d1 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 26 Jun 2008 11:21:34 +0200 Subject: Add generic helpers for arch IPI function calls This adds kernel/smp.c which contains helpers for IPI function calls. In addition to supporting the existing smp_call_function() in a more efficient manner, it also adds a more scalable variant called smp_call_function_single() for calling a given function on a single CPU only. The core of this is based on the x86-64 patch from Nick Piggin, lots of changes since then. "Alan D. Brunelle" has contributed lots of fixes and suggestions as well. Also thanks to Paul E. McKenney for reviewing RCU usage and getting rid of the data allocation fallback deadlock. Acked-by: Ingo Molnar Reviewed-by: Paul E. McKenney Signed-off-by: Jens Axboe --- arch/Kconfig | 3 + arch/sparc64/kernel/smp.c | 11 +- include/linux/smp.h | 35 ++++- init/main.c | 2 + kernel/Makefile | 1 + kernel/smp.c | 383 ++++++++++++++++++++++++++++++++++++++++++++++ 6 files changed, 428 insertions(+), 7 deletions(-) create mode 100644 kernel/smp.c (limited to 'init') diff --git a/arch/Kconfig b/arch/Kconfig index 3ea332b009e5..ad89a33d8c6e 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -39,3 +39,6 @@ config HAVE_KRETPROBES config HAVE_DMA_ATTRS def_bool n + +config USE_GENERIC_SMP_HELPERS + def_bool n diff --git a/arch/sparc64/kernel/smp.c b/arch/sparc64/kernel/smp.c index fa63c68a1819..b82d017a1744 100644 --- a/arch/sparc64/kernel/smp.c +++ b/arch/sparc64/kernel/smp.c @@ -816,8 +816,9 @@ extern unsigned long xcall_call_function; * You must not call this function with disabled interrupts or from a * hardware interrupt handler or from a bottom half handler. */ -static int smp_call_function_mask(void (*func)(void *info), void *info, - int nonatomic, int wait, cpumask_t mask) +static int sparc64_smp_call_function_mask(void (*func)(void *info), void *info, + int nonatomic, int wait, + cpumask_t mask) { struct call_data_struct data; int cpus; @@ -855,8 +856,8 @@ out_unlock: int smp_call_function(void (*func)(void *info), void *info, int nonatomic, int wait) { - return smp_call_function_mask(func, info, nonatomic, wait, - cpu_online_map); + return sparc64_smp_call_function_mask(func, info, nonatomic, wait, + cpu_online_map); } void smp_call_function_client(int irq, struct pt_regs *regs) @@ -893,7 +894,7 @@ static void tsb_sync(void *info) void smp_tsb_sync(struct mm_struct *mm) { - smp_call_function_mask(tsb_sync, mm, 0, 1, mm->cpu_vm_mask); + sparc64_smp_call_function_mask(tsb_sync, mm, 0, 1, mm->cpu_vm_mask); } extern unsigned long xcall_flush_tlb_mm; diff --git a/include/linux/smp.h b/include/linux/smp.h index 55232ccf9cfd..eac3e062250f 100644 --- a/include/linux/smp.h +++ b/include/linux/smp.h @@ -7,9 +7,19 @@ */ #include +#include +#include +#include extern void cpu_idle(void); +struct call_single_data { + struct list_head list; + void (*func) (void *info); + void *info; + unsigned int flags; +}; + #ifdef CONFIG_SMP #include @@ -53,9 +63,28 @@ extern void smp_cpus_done(unsigned int max_cpus); * Call a function on all other processors */ int smp_call_function(void(*func)(void *info), void *info, int retry, int wait); - +int smp_call_function_mask(cpumask_t mask, void(*func)(void *info), void *info, + int wait); int smp_call_function_single(int cpuid, void (*func) (void *info), void *info, int retry, int wait); +void __smp_call_function_single(int cpuid, struct call_single_data *data); + +/* + * Generic and arch helpers + */ +#ifdef CONFIG_USE_GENERIC_SMP_HELPERS +void generic_smp_call_function_single_interrupt(void); +void generic_smp_call_function_interrupt(void); +void init_call_single_data(void); +void ipi_call_lock(void); +void ipi_call_unlock(void); +void ipi_call_lock_irq(void); +void ipi_call_unlock_irq(void); +#else +static inline void init_call_single_data(void) +{ +} +#endif /* * Call a function on all processors @@ -112,7 +141,9 @@ static inline void smp_send_reschedule(int cpu) { } }) #define smp_call_function_mask(mask, func, info, wait) \ (up_smp_call_function(func, info)) - +static inline void init_call_single_data(void) +{ +} #endif /* !SMP */ /* diff --git a/init/main.c b/init/main.c index f7fb20021d48..1efcccff1bdb 100644 --- a/init/main.c +++ b/init/main.c @@ -31,6 +31,7 @@ #include #include #include +#include #include #include #include @@ -779,6 +780,7 @@ static void __init do_pre_smp_initcalls(void) { extern int spawn_ksoftirqd(void); + init_call_single_data(); migration_init(); spawn_ksoftirqd(); if (!nosoftlockup) diff --git a/kernel/Makefile b/kernel/Makefile index 1c9938addb9d..9fa57976f252 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -28,6 +28,7 @@ obj-$(CONFIG_DEBUG_RT_MUTEXES) += rtmutex-debug.o obj-$(CONFIG_RT_MUTEX_TESTER) += rtmutex-tester.o obj-$(CONFIG_GENERIC_ISA_DMA) += dma.o obj-$(CONFIG_SMP) += cpu.o spinlock.o +obj-$(CONFIG_USE_GENERIC_SMP_HELPERS) += smp.o obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock.o obj-$(CONFIG_PROVE_LOCKING) += spinlock.o obj-$(CONFIG_UID16) += uid16.o diff --git a/kernel/smp.c b/kernel/smp.c new file mode 100644 index 000000000000..f77b75c027ad --- /dev/null +++ b/kernel/smp.c @@ -0,0 +1,383 @@ +/* + * Generic helpers for smp ipi calls + * + * (C) Jens Axboe 2008 + * + */ +#include +#include +#include +#include +#include + +static DEFINE_PER_CPU(struct call_single_queue, call_single_queue); +static LIST_HEAD(call_function_queue); +__cacheline_aligned_in_smp DEFINE_SPINLOCK(call_function_lock); + +enum { + CSD_FLAG_WAIT = 0x01, + CSD_FLAG_ALLOC = 0x02, +}; + +struct call_function_data { + struct call_single_data csd; + spinlock_t lock; + unsigned int refs; + cpumask_t cpumask; + struct rcu_head rcu_head; +}; + +struct call_single_queue { + struct list_head list; + spinlock_t lock; +}; + +void __cpuinit init_call_single_data(void) +{ + int i; + + for_each_possible_cpu(i) { + struct call_single_queue *q = &per_cpu(call_single_queue, i); + + spin_lock_init(&q->lock); + INIT_LIST_HEAD(&q->list); + } +} + +static void csd_flag_wait(struct call_single_data *data) +{ + /* Wait for response */ + do { + /* + * We need to see the flags store in the IPI handler + */ + smp_mb(); + if (!(data->flags & CSD_FLAG_WAIT)) + break; + cpu_relax(); + } while (1); +} + +/* + * Insert a previously allocated call_single_data element for execution + * on the given CPU. data must already have ->func, ->info, and ->flags set. + */ +static void generic_exec_single(int cpu, struct call_single_data *data) +{ + struct call_single_queue *dst = &per_cpu(call_single_queue, cpu); + int wait = data->flags & CSD_FLAG_WAIT, ipi; + unsigned long flags; + + spin_lock_irqsave(&dst->lock, flags); + ipi = list_empty(&dst->list); + list_add_tail(&data->list, &dst->list); + spin_unlock_irqrestore(&dst->lock, flags); + + if (ipi) + arch_send_call_function_single_ipi(cpu); + + if (wait) + csd_flag_wait(data); +} + +static void rcu_free_call_data(struct rcu_head *head) +{ + struct call_function_data *data; + + data = container_of(head, struct call_function_data, rcu_head); + + kfree(data); +} + +/* + * Invoked by arch to handle an IPI for call function. Must be called with + * interrupts disabled. + */ +void generic_smp_call_function_interrupt(void) +{ + struct call_function_data *data; + int cpu = get_cpu(); + + /* + * It's ok to use list_for_each_rcu() here even though we may delete + * 'pos', since list_del_rcu() doesn't clear ->next + */ + rcu_read_lock(); + list_for_each_entry_rcu(data, &call_function_queue, csd.list) { + int refs; + + if (!cpu_isset(cpu, data->cpumask)) + continue; + + data->csd.func(data->csd.info); + + spin_lock(&data->lock); + cpu_clear(cpu, data->cpumask); + WARN_ON(data->refs == 0); + data->refs--; + refs = data->refs; + spin_unlock(&data->lock); + + if (refs) + continue; + + spin_lock(&call_function_lock); + list_del_rcu(&data->csd.list); + spin_unlock(&call_function_lock); + + if (data->csd.flags & CSD_FLAG_WAIT) { + /* + * serialize stores to data with the flag clear + * and wakeup + */ + smp_wmb(); + data->csd.flags &= ~CSD_FLAG_WAIT; + } else + call_rcu(&data->rcu_head, rcu_free_call_data); + } + rcu_read_unlock(); + + put_cpu(); +} + +/* + * Invoked by arch to handle an IPI for call function single. Must be called + * from the arch with interrupts disabled. + */ +void generic_smp_call_function_single_interrupt(void) +{ + struct call_single_queue *q = &__get_cpu_var(call_single_queue); + LIST_HEAD(list); + + /* + * Need to see other stores to list head for checking whether + * list is empty without holding q->lock + */ + smp_mb(); + while (!list_empty(&q->list)) { + unsigned int data_flags; + + spin_lock(&q->lock); + list_replace_init(&q->list, &list); + spin_unlock(&q->lock); + + while (!list_empty(&list)) { + struct call_single_data *data; + + data = list_entry(list.next, struct call_single_data, + list); + list_del(&data->list); + + /* + * 'data' can be invalid after this call if + * flags == 0 (when called through + * generic_exec_single(), so save them away before + * making the call. + */ + data_flags = data->flags; + + data->func(data->info); + + if (data_flags & CSD_FLAG_WAIT) { + smp_wmb(); + data->flags &= ~CSD_FLAG_WAIT; + } else if (data_flags & CSD_FLAG_ALLOC) + kfree(data); + } + /* + * See comment on outer loop + */ + smp_mb(); + } +} + +/* + * smp_call_function_single - Run a function on a specific CPU + * @func: The function to run. This must be fast and non-blocking. + * @info: An arbitrary pointer to pass to the function. + * @retry: Unused + * @wait: If true, wait until function has completed on other CPUs. + * + * Returns 0 on success, else a negative status code. Note that @wait + * will be implicitly turned on in case of allocation failures, since + * we fall back to on-stack allocation. + */ +int smp_call_function_single(int cpu, void (*func) (void *info), void *info, + int retry, int wait) +{ + struct call_single_data d; + unsigned long flags; + /* prevent preemption and reschedule on another processor */ + int me = get_cpu(); + + /* Can deadlock when called with interrupts disabled */ + WARN_ON(irqs_disabled()); + + if (cpu == me) { + local_irq_save(flags); + func(info); + local_irq_restore(flags); + } else { + struct call_single_data *data = NULL; + + if (!wait) { + data = kmalloc(sizeof(*data), GFP_ATOMIC); + if (data) + data->flags = CSD_FLAG_ALLOC; + } + if (!data) { + data = &d; + data->flags = CSD_FLAG_WAIT; + } + + data->func = func; + data->info = info; + generic_exec_single(cpu, data); + } + + put_cpu(); + return 0; +} +EXPORT_SYMBOL(smp_call_function_single); + +/** + * __smp_call_function_single(): Run a function on another CPU + * @cpu: The CPU to run on. + * @data: Pre-allocated and setup data structure + * + * Like smp_call_function_single(), but allow caller to pass in a pre-allocated + * data structure. Useful for embedding @data inside other structures, for + * instance. + * + */ +void __smp_call_function_single(int cpu, struct call_single_data *data) +{ + /* Can deadlock when called with interrupts disabled */ + WARN_ON((data->flags & CSD_FLAG_WAIT) && irqs_disabled()); + + generic_exec_single(cpu, data); +} + +/** + * smp_call_function_mask(): Run a function on a set of other CPUs. + * @mask: The set of cpus to run on. + * @func: The function to run. This must be fast and non-blocking. + * @info: An arbitrary pointer to pass to the function. + * @wait: If true, wait (atomically) until function has completed on other CPUs. + * + * Returns 0 on success, else a negative status code. + * + * If @wait is true, then returns once @func has returned. Note that @wait + * will be implicitly turned on in case of allocation failures, since + * we fall back to on-stack allocation. + * + * You must not call this function with disabled interrupts or from a + * hardware interrupt handler or from a bottom half handler. Preemption + * must be disabled when calling this function. + */ +int smp_call_function_mask(cpumask_t mask, void (*func)(void *), void *info, + int wait) +{ + struct call_function_data d; + struct call_function_data *data = NULL; + cpumask_t allbutself; + unsigned long flags; + int cpu, num_cpus; + + /* Can deadlock when called with interrupts disabled */ + WARN_ON(irqs_disabled()); + + cpu = smp_processor_id(); + allbutself = cpu_online_map; + cpu_clear(cpu, allbutself); + cpus_and(mask, mask, allbutself); + num_cpus = cpus_weight(mask); + + /* + * If zero CPUs, return. If just a single CPU, turn this request + * into a targetted single call instead since it's faster. + */ + if (!num_cpus) + return 0; + else if (num_cpus == 1) { + cpu = first_cpu(mask); + return smp_call_function_single(cpu, func, info, 0, wait); + } + + if (!wait) { + data = kmalloc(sizeof(*data), GFP_ATOMIC); + if (data) + data->csd.flags = CSD_FLAG_ALLOC; + } + if (!data) { + data = &d; + data->csd.flags = CSD_FLAG_WAIT; + } + + spin_lock_init(&data->lock); + data->csd.func = func; + data->csd.info = info; + data->refs = num_cpus; + data->cpumask = mask; + + spin_lock_irqsave(&call_function_lock, flags); + list_add_tail_rcu(&data->csd.list, &call_function_queue); + spin_unlock_irqrestore(&call_function_lock, flags); + + /* Send a message to all CPUs in the map */ + arch_send_call_function_ipi(mask); + + /* optionally wait for the CPUs to complete */ + if (wait) + csd_flag_wait(&data->csd); + + return 0; +} +EXPORT_SYMBOL(smp_call_function_mask); + +/** + * smp_call_function(): Run a function on all other CPUs. + * @func: The function to run. This must be fast and non-blocking. + * @info: An arbitrary pointer to pass to the function. + * @natomic: Unused + * @wait: If true, wait (atomically) until function has completed on other CPUs. + * + * Returns 0 on success, else a negative status code. + * + * If @wait is true, then returns once @func has returned; otherwise + * it returns just before the target cpu calls @func. In case of allocation + * failure, @wait will be implicitly turned on. + * + * You must not call this function with disabled interrupts or from a + * hardware interrupt handler or from a bottom half handler. + */ +int smp_call_function(void (*func)(void *), void *info, int natomic, int wait) +{ + int ret; + + preempt_disable(); + ret = smp_call_function_mask(cpu_online_map, func, info, wait); + preempt_enable(); + return ret; +} +EXPORT_SYMBOL(smp_call_function); + +void ipi_call_lock(void) +{ + spin_lock(&call_function_lock); +} + +void ipi_call_unlock(void) +{ + spin_unlock(&call_function_lock); +} + +void ipi_call_lock_irq(void) +{ + spin_lock_irq(&call_function_lock); +} + +void ipi_call_unlock_irq(void) +{ + spin_unlock_irq(&call_function_lock); +} -- cgit v1.2.3-59-g8ed1b From 2d62f488585405bc9108c47cb06957397cfd1059 Mon Sep 17 00:00:00 2001 From: Adrian Hunter Date: Thu, 31 Jan 2008 17:25:00 +0200 Subject: do_mounts: allow UBI root device name Similarly to MTD devices, allow UBI devices. Signed-off-by: Adrian Hunter --- init/do_mounts.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'init') diff --git a/init/do_mounts.c b/init/do_mounts.c index 660c1e50c91b..a1de1bf3d6b9 100644 --- a/init/do_mounts.c +++ b/init/do_mounts.c @@ -372,7 +372,8 @@ void __init prepare_namespace(void) if (saved_root_name[0]) { root_device_name = saved_root_name; - if (!strncmp(root_device_name, "mtd", 3)) { + if (!strncmp(root_device_name, "mtd", 3) || + !strncmp(root_device_name, "ubi", 3)) { mount_block_root(root_device_name, root_mountflags); goto out; } -- cgit v1.2.3-59-g8ed1b