^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 1) /* SPDX-License-Identifier: GPL-2.0 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 2) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 3) * This program is free software; you can redistribute it and/or modify
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 4) * it under the terms of the GNU General Public License as published by
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 5) * the Free Software Foundation; either version 2 of the License, or
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 6) * (at your option) any later version.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 7) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 8) * This program is distributed in the hope that it will be useful,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 9) * but WITHOUT ANY WARRANTY; without even the implied warranty of
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) * GNU General Public License for more details.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) * Authors: Waiman Long <waiman.long@hpe.com>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) * Collect locking event counts
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) #include <linux/debugfs.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) #include <linux/sched.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) #include <linux/sched/clock.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) #include <linux/fs.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) #include "lock_events.h"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) #undef LOCK_EVENT
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) #define LOCK_EVENT(name) [LOCKEVENT_ ## name] = #name,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) #define LOCK_EVENTS_DIR "lock_event_counts"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) * When CONFIG_LOCK_EVENT_COUNTS is enabled, event counts of different
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) * types of locks will be reported under the <debugfs>/lock_event_counts/
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) * directory. See lock_events_list.h for the list of available locking
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) * events.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) * Writing to the special ".reset_counts" file will reset all the above
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) * locking event counts. This is a very slow operation and so should not
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) * be done frequently.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) * These event counts are implemented as per-cpu variables which are
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) * summed and computed whenever the corresponding debugfs files are read. This
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) * minimizes added overhead making the counts usable even in a production
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) * environment.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) static const char * const lockevent_names[lockevent_num + 1] = {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) #include "lock_events_list.h"
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) [LOCKEVENT_reset_cnts] = ".reset_counts",
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) * Per-cpu counts
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) DEFINE_PER_CPU(unsigned long, lockevents[lockevent_num]);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) * The lockevent_read() function can be overridden.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) ssize_t __weak lockevent_read(struct file *file, char __user *user_buf,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) size_t count, loff_t *ppos)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64) char buf[64];
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65) int cpu, id, len;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 66) u64 sum = 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 67)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 68) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 69) * Get the counter ID stored in file->f_inode->i_private
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 70) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 71) id = (long)file_inode(file)->i_private;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 72)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 73) if (id >= lockevent_num)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 74) return -EBADF;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 75)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 76) for_each_possible_cpu(cpu)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 77) sum += per_cpu(lockevents[id], cpu);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 78) len = snprintf(buf, sizeof(buf) - 1, "%llu\n", sum);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 79)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 80) return simple_read_from_buffer(user_buf, count, ppos, buf, len);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 81) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 82)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 83) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 84) * Function to handle write request
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 85) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 86) * When idx = reset_cnts, reset all the counts.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 87) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 88) static ssize_t lockevent_write(struct file *file, const char __user *user_buf,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 89) size_t count, loff_t *ppos)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 90) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 91) int cpu;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 92)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 93) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 94) * Get the counter ID stored in file->f_inode->i_private
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 95) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 96) if ((long)file_inode(file)->i_private != LOCKEVENT_reset_cnts)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 97) return count;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 98)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 99) for_each_possible_cpu(cpu) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) int i;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101) unsigned long *ptr = per_cpu_ptr(lockevents, cpu);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103) for (i = 0 ; i < lockevent_num; i++)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104) WRITE_ONCE(ptr[i], 0);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106) return count;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) * Debugfs data structures
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112) static const struct file_operations fops_lockevent = {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113) .read = lockevent_read,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114) .write = lockevent_write,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115) .llseek = default_llseek,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118) #ifdef CONFIG_PARAVIRT_SPINLOCKS
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) #include <asm/paravirt.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121) static bool __init skip_lockevent(const char *name)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123) static int pv_on __initdata = -1;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) if (pv_on < 0)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126) pv_on = !pv_is_native_spin_unlock();
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128) * Skip PV qspinlock events on bare metal.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130) if (!pv_on && !memcmp(name, "pv_", 3))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131) return true;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132) return false;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134) #else
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135) static inline bool skip_lockevent(const char *name)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137) return false;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139) #endif
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142) * Initialize debugfs for the locking event counts.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) static int __init init_lockevent_counts(void)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) struct dentry *d_counts = debugfs_create_dir(LOCK_EVENTS_DIR, NULL);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) int i;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149) if (!d_counts)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150) goto out;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153) * Create the debugfs files
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 155) * As reading from and writing to the stat files can be slow, only
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 156) * root is allowed to do the read/write to limit impact to system
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 157) * performance.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 158) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 159) for (i = 0; i < lockevent_num; i++) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 160) if (skip_lockevent(lockevent_names[i]))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 161) continue;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 162) if (!debugfs_create_file(lockevent_names[i], 0400, d_counts,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 163) (void *)(long)i, &fops_lockevent))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 164) goto fail_undo;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 165) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 166)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 167) if (!debugfs_create_file(lockevent_names[LOCKEVENT_reset_cnts], 0200,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 168) d_counts, (void *)(long)LOCKEVENT_reset_cnts,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 169) &fops_lockevent))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 170) goto fail_undo;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 171)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 172) return 0;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 173) fail_undo:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 174) debugfs_remove_recursive(d_counts);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 175) out:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 176) pr_warn("Could not create '%s' debugfs entries\n", LOCK_EVENTS_DIR);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 177) return -ENOMEM;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 178) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 179) fs_initcall(init_lockevent_counts);
Orange Pi5 kernel
Deprecated Linux kernel 5.10.110 for OrangePi 5/5B/5+ boards
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