Messages in this thread Patch in this message | | | Date | Tue, 15 Apr 2008 17:25:15 +0530 | From | "K. Prasad" <> | Subject | [RFC PATCH 2/2] Marker handler for the probes in futex file |
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These files define and implement marker handlers for the probes in futex.c. They may be built by choosing the CONFIG_FUTEX_DEBUG option (can be built as a kernel module also).
They export data to the user using debugfs_printk and the output is available in futex_debug_trace/ directory under the debugfs mount. Separate directories under this are created for each marker probe.
Signed-off-by: K.Prasad <prasad@linux.vnet.ibm.com> --- include/linux/futex_markers.h | 63 +++++++++++++ init/Kconfig | 13 ++ kernel/Makefile | 1 kernel/futex_markers.c | 201 ++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 278 insertions(+)
Index: linux-2.6.25-rc8-mm1/init/Kconfig =================================================================== --- linux-2.6.25-rc8-mm1.orig/init/Kconfig +++ linux-2.6.25-rc8-mm1/init/Kconfig @@ -646,6 +646,19 @@ config FUTEX support for "fast userspace mutexes". The resulting kernel may not run glibc-based applications correctly. +config FUTEX_DEBUG + tristate "Enable debugging for Futex - currently stats in debugfs" + depends on FUTEX + depends on DEBUG_FS && MARKERS && TRACE + default m + help + This option provides debugging data for Futex system calls + in debugfs. + + Say Y/M here if you want to enable Futex debugging + in-kernel/module. + Say N if you are unsure. + config ANON_INODES bool Index: linux-2.6.25-rc8-mm1/kernel/futex_markers.c =================================================================== --- /dev/null +++ linux-2.6.25-rc8-mm1/kernel/futex_markers.c @@ -0,0 +1,201 @@ +/* + * futex_markers.c - Marker handler for probes in futex.c + * + * Copyright IBM Corp. 2008 + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it would 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. + */ + +#include <linux/types.h> +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/spinlock.h> +#include <linux/module.h> +#include <linux/completion.h> +#include <linux/moduleparam.h> +#include <linux/mutex.h> +#include <linux/debugfs.h> +#include <linux/futex_markers.h> + +#define FUTEX_DEBUG_STRING_SIZE 1024 +#define FUTEX_DEBUG_DIR_MAXLEN 25 + +static void futex_event_debug_worker(const char *marker_name, + const char *format_str, + enum futex_ops_ futex_event, va_list *ap); + +/* + * This function helps to direct the output to one of the directories + */ +static inline char *choose_output_dir(enum futex_ops_ futex_event) +{ + char *temp = NULL; + + switch (futex_event) { + case do_futex_probe: + temp = "do_futex_probe_debug"; + break; + case futex_wait_called: + case futex_wait_uval: + case futex_wait_after_sched: + case futex_wait_failed: + temp = "futex_wait_debug"; + break; + case futex_wake_called: + case futex_wake_failed: + temp = "futex_wake_debug"; + break; + case futex_cmp_requeue_called: + case futex_cmp_requeue_uaddr2_failed: + case futex_cmp_requeue_failed: + temp = "futex_cmp_requeue_debug"; + break; + case futex_lock_pi_called: + case futex_lock_pi_failed: + temp = "futex_lock_pi_debug"; + break; + case futex_unlock_pi_called: + case futex_unlock_pi_failed: + temp = "futex_unlock_pi_debug"; + break; + } + return temp; +} + +/* + * Use the macro to define the other marker handlers + */ +DEFINE_FUTEX_OP_MARKER_HANDLER(futex_wake_called); +DEFINE_FUTEX_OP_MARKER_HANDLER(futex_cmp_requeue_called); +DEFINE_FUTEX_OP_MARKER_HANDLER(futex_wait_called); +DEFINE_FUTEX_OP_MARKER_HANDLER(futex_wait_uval); +DEFINE_FUTEX_OP_MARKER_HANDLER(futex_wait_after_sched); +DEFINE_FUTEX_OP_MARKER_HANDLER(futex_lock_pi_called); +DEFINE_FUTEX_OP_MARKER_HANDLER(futex_unlock_pi_called); + +DEFINE_FUTEX_OP_MARKER_HANDLER(futex_wait_failed); +DEFINE_FUTEX_OP_MARKER_HANDLER(futex_wake_failed); +DEFINE_FUTEX_OP_MARKER_HANDLER(futex_cmp_requeue_failed); +DEFINE_FUTEX_OP_MARKER_HANDLER(futex_cmp_requeue_uaddr2_failed); +DEFINE_FUTEX_OP_MARKER_HANDLER(futex_lock_pi_failed); +DEFINE_FUTEX_OP_MARKER_HANDLER(futex_unlock_pi_failed); + +DEFINE_FUTEX_OP_MARKER_HANDLER(do_futex_probe); + +static struct futex_debug_probe futex_debug_probe_array[] = +{ + INIT_FUTEX_DEBUG_PROBE(futex_wake_called, + "uaddr:%p fshared:%p nr_wake:%d bitset:%d"), + INIT_FUTEX_DEBUG_PROBE(futex_wait_called, + "uaddr:%p fshared:%p val:%u abs_time:%p bitset:%d"), + INIT_FUTEX_DEBUG_PROBE(futex_wait_uval, "uaddr:%p uval:%u"), + INIT_FUTEX_DEBUG_PROBE(futex_wait_after_sched, "uaddr:%p"), + INIT_FUTEX_DEBUG_PROBE(futex_cmp_requeue_called, + "uaddr1:%p fshared:%p uaddr2:%p nr_wake:%d " + "nr_requeue:%d cmpval:%p"), + INIT_FUTEX_DEBUG_PROBE(futex_lock_pi_called, + "uaddr:%p fshared:%p detect:%d time:%p trylock:%d"), + INIT_FUTEX_DEBUG_PROBE(futex_unlock_pi_called, "uaddr:%p fshared:%p"), + + INIT_FUTEX_DEBUG_PROBE(futex_wait_failed, "uaddr:%p ret:%d"), + INIT_FUTEX_DEBUG_PROBE(futex_wake_failed, "uaddr:%p ret:%d"), + INIT_FUTEX_DEBUG_PROBE(futex_cmp_requeue_failed, "uaddr1:%p ret:%d"), + INIT_FUTEX_DEBUG_PROBE(futex_cmp_requeue_uaddr2_failed, + "uaddr1:%p uaddr2:%p ret:%d"), + INIT_FUTEX_DEBUG_PROBE(futex_lock_pi_failed, "uaddr:%p ret:%d"), + INIT_FUTEX_DEBUG_PROBE(futex_unlock_pi_failed, "uaddr:%p ret:%d"), + + INIT_FUTEX_DEBUG_PROBE(do_futex_probe, + "uaddr: %lu op:%d val:%lu timeout:%p " + "uaddr2:%lu val2:%lu val3:%lu ret:%d") +}; + +static void futex_event_debug_worker(const char *marker_name, + const char *format_str, + enum futex_ops_ futex_event, va_list *ap) +{ + unsigned long long temp_ts = 0; + struct debugfs_printk_data *dpk; + char *print_string; + int err_condition = 0; + + /* Capture the kernel timestamp as soon as we enter the handler */ + temp_ts = ktime_to_ns(ktime_get()); + + + dpk = kzalloc(sizeof(*dpk), GFP_KERNEL); + if (!dpk) + err_condition = 1; + + dpk->parent_dir = FUTEX_TRACE_ROOT_DIR; + dpk->dir = choose_output_dir(futex_event); + print_string = kzalloc(FUTEX_DEBUG_STRING_SIZE, GFP_KERNEL); + if (!print_string) { + err_condition = 1; + goto out; + } + + snprintf(print_string, FUTEX_DEBUG_STRING_SIZE, + "%s TS:%llu PID:%u Process:%s %s\n", marker_name, + temp_ts, current->pid, current->comm, format_str); + + debugfs_printk(dpk, print_string, ap); + + /* Exit code. Free the memory held */ + out: + kfree(dpk); + + if (err_condition) + printk(KERN_ERR "Unable to find required free memory. " + "Futex Debug message discarded"); +} + +static int __init futex_debug_init(void) +{ + int ret; + int i; + struct futex_debug_probe *p; + + for (i = 0; i < ARRAY_SIZE(futex_debug_probe_array); i++) { + p = &futex_debug_probe_array[i]; + ret = marker_probe_register(p->name, p->format, + p->probe_func, p); + if (ret) + printk(KERN_INFO "Unable to register Futex Debug " + "probe %s\n", futex_debug_probe_array[i].name); + + if (ret) + printk(KERN_INFO "Unable to arm Futex Debug probe %s\n", + p->name); + } + printk(KERN_INFO "Futex Debug markers registered\n"); + + return ret; +} + +static void __exit futex_debug_cleanup(void) +{ + int i; + struct futex_debug_probe *p; + + for (i = 0; i < ARRAY_SIZE(futex_debug_probe_array); i++) { + p = &futex_debug_probe_array[i]; + marker_probe_unregister(p->name, p->probe_func, p); + } + printk(KERN_INFO "Futex Debug markers unregistered\n"); + + trace_cleanup_all(FUTEX_TRACE_ROOT_DIR); +} + +MODULE_LICENSE("GPL"); + +module_init(futex_debug_init); +module_exit(futex_debug_cleanup); Index: linux-2.6.25-rc8-mm1/include/linux/futex_markers.h =================================================================== --- /dev/null +++ linux-2.6.25-rc8-mm1/include/linux/futex_markers.h @@ -0,0 +1,63 @@ +/* + * futex_markers.h + * + * Copyright IBM Corp. 2008 + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it would 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. + */ + +#include <linux/types.h> +#include <linux/kernel.h> +#include <linux/marker.h> +#include <linux/ktime.h> +#include <linux/trace.h> + +#define FUTEX_TRACE_BUF_SIZE 4096 +#define FUTEX_TRACE_SUB_BUF_NR 40 +#define FUTEX_TRACE_ROOT_DIR "futex_debug_trace" + +struct futex_debug_probe { + char *name; + char *format; + marker_probe_func *probe_func; +}; + +enum futex_ops_ { + do_futex_probe, + futex_wait_called, futex_wait_uval, + futex_wait_after_sched, futex_wait_failed, + futex_wake_called, futex_wake_failed, + futex_cmp_requeue_called, futex_cmp_requeue_uaddr2_failed, + futex_cmp_requeue_failed, + futex_lock_pi_called, futex_lock_pi_failed, + futex_unlock_pi_called, futex_unlock_pi_failed +}; + +#define DEFINE_FUTEX_OP_MARKER_HANDLER(futex_event) \ +static void futex_event##_callback(const struct marker *mdata, \ + void *private_data, const char *format, va_list *ap) \ +{ \ + /* \ + * futex_event - Used to identify the type of futex event (enum) \ + * __stringify(futex_event) - helps print the type of futex event as a \ + * string in trace_printf() \ + * ap - Contains the parameters exported to the marker handler \ + */ \ + futex_event_debug_worker(mdata->name, mdata->format, futex_event, ap); \ + \ +} + +#define INIT_FUTEX_DEBUG_PROBE(futex_debug_event, format_specifier) \ +{ \ + .name = __stringify(futex_debug_event), \ + .format = format_specifier, \ + .probe_func = futex_debug_event##_callback \ +} Index: linux-2.6.25-rc8-mm1/kernel/Makefile =================================================================== --- linux-2.6.25-rc8-mm1.orig/kernel/Makefile +++ linux-2.6.25-rc8-mm1/kernel/Makefile @@ -23,6 +23,7 @@ obj-$(CONFIG_FUTEX) += futex.o ifeq ($(CONFIG_COMPAT),y) obj-$(CONFIG_FUTEX) += futex_compat.o endif +obj-$(CONFIG_FUTEX_DEBUG) += futex_markers.o obj-$(CONFIG_RT_MUTEXES) += rtmutex.o obj-$(CONFIG_DEBUG_RT_MUTEXES) += rtmutex-debug.o obj-$(CONFIG_RT_MUTEX_TESTER) += rtmutex-tester.o
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