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![Greg Kroah-Hartman](/assets/img/avatar_default.png)
When calling debugfs functions, there is no need to ever check the return value. The function can work or not, but the code logic should never do something different based on this. Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Paul Burton <paul.burton@mips.com> Cc: James Hogan <jhogan@kernel.org> Cc: Yangtao Li <tiny.windzz@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Mathieu Malaterre <malat@debian.org> Cc: Huacai Chen <chenhc@lemote.com> Cc: Marcin Nowakowski <marcin.nowakowski@mips.com> Cc: Yasha Cherikovsky <yasha.che3@gmail.com> Cc: linux-mips@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Paul Burton <paul.burton@mips.com>
127 lines
2.2 KiB
C
127 lines
2.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/init.h>
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#include <linux/kthread.h>
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#include <linux/hrtimer.h>
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#include <linux/fs.h>
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#include <linux/debugfs.h>
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#include <linux/export.h>
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#include <linux/spinlock.h>
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#include <asm/debug.h>
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static int ss_get(void *data, u64 *val)
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{
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ktime_t start, finish;
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int loops;
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int cont;
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DEFINE_RAW_SPINLOCK(ss_spin);
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loops = 1000000;
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cont = 1;
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start = ktime_get();
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while (cont) {
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raw_spin_lock(&ss_spin);
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loops--;
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if (loops == 0)
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cont = 0;
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raw_spin_unlock(&ss_spin);
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}
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finish = ktime_get();
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*val = ktime_us_delta(finish, start);
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return 0;
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}
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DEFINE_SIMPLE_ATTRIBUTE(fops_ss, ss_get, NULL, "%llu\n");
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struct spin_multi_state {
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raw_spinlock_t lock;
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atomic_t start_wait;
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atomic_t enter_wait;
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atomic_t exit_wait;
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int loops;
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};
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struct spin_multi_per_thread {
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struct spin_multi_state *state;
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ktime_t start;
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};
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static int multi_other(void *data)
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{
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int loops;
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int cont;
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struct spin_multi_per_thread *pt = data;
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struct spin_multi_state *s = pt->state;
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loops = s->loops;
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cont = 1;
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atomic_dec(&s->enter_wait);
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while (atomic_read(&s->enter_wait))
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; /* spin */
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pt->start = ktime_get();
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atomic_dec(&s->start_wait);
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while (atomic_read(&s->start_wait))
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; /* spin */
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while (cont) {
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raw_spin_lock(&s->lock);
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loops--;
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if (loops == 0)
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cont = 0;
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raw_spin_unlock(&s->lock);
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}
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atomic_dec(&s->exit_wait);
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while (atomic_read(&s->exit_wait))
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; /* spin */
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return 0;
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}
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static int multi_get(void *data, u64 *val)
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{
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ktime_t finish;
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struct spin_multi_state ms;
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struct spin_multi_per_thread t1, t2;
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ms.lock = __RAW_SPIN_LOCK_UNLOCKED("multi_get");
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ms.loops = 1000000;
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atomic_set(&ms.start_wait, 2);
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atomic_set(&ms.enter_wait, 2);
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atomic_set(&ms.exit_wait, 2);
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t1.state = &ms;
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t2.state = &ms;
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kthread_run(multi_other, &t2, "multi_get");
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multi_other(&t1);
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finish = ktime_get();
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*val = ktime_us_delta(finish, t1.start);
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return 0;
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}
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DEFINE_SIMPLE_ATTRIBUTE(fops_multi, multi_get, NULL, "%llu\n");
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static int __init spinlock_test(void)
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{
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debugfs_create_file("spin_single", S_IRUGO, mips_debugfs_dir, NULL,
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&fops_ss);
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debugfs_create_file("spin_multi", S_IRUGO, mips_debugfs_dir, NULL,
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&fops_multi);
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return 0;
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}
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device_initcall(spinlock_test);
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