1 /* SPDX-License-Identifier: GPL-2.0 */
6  * Protect against 64-bit values tearing on 32-bit architectures. This is
11  * -  Use a seqcount on 32-bit SMP, only disable preemption for 32-bit UP.
12  * -  The whole thing is a no-op on 64-bit architectures.
34  *    seqcounts are not used for UP kernels). 32-bit UP stat readers could read
35  *    corrupted 64-bit values otherwise.
45  *   u64_stats_update_begin(&stats->syncp);
46  *   u64_stats_add(&stats->bytes64, len); // non atomic operation
47  *   u64_stats_inc(&stats->packets64);    // non atomic operation
48  *   u64_stats_update_end(&stats->syncp);
54  * unsigned int start;
57  *         start = u64_stats_fetch_begin(&stats->syncp);
58  *         tbytes = u64_stats_read(&stats->bytes64); // non atomic operation
59  *         tpackets = u64_stats_read(&stats->packets64); // non atomic operation
60  * } while (u64_stats_fetch_retry(&stats->syncp, start));
83 	return local64_read(&p->v);  in u64_stats_read()
88 	local64_add(val, &p->v);  in u64_stats_add()
93 	local64_inc(&p->v);  in u64_stats_inc()
104 	return p->v;  in u64_stats_read()
109 	p->v += val;  in u64_stats_add()
114 	p->v++;  in u64_stats_inc()
121 	seqcount_init(&syncp->seq);  in u64_stats_init()
128 	write_seqcount_begin(&syncp->seq);  in u64_stats_update_begin()
135 	write_seqcount_end(&syncp->seq);  in u64_stats_update_end()
146 	write_seqcount_begin(&syncp->seq);  in u64_stats_update_begin_irqsave()
156 	write_seqcount_end(&syncp->seq);  in u64_stats_update_end_irqrestore()
164 	return read_seqcount_begin(&syncp->seq);  in __u64_stats_fetch_begin()
179 					 unsigned int start)  in __u64_stats_fetch_retry()  argument
182 	return read_seqcount_retry(&syncp->seq, start);  in __u64_stats_fetch_retry()
189 					 unsigned int start)  in u64_stats_fetch_retry()  argument
194 	return __u64_stats_fetch_retry(syncp, start);  in u64_stats_fetch_retry()
199  * - SMP 32bit arches use seqcount protection, irq safe.
200  * - UP 32bit must disable irqs.
201  * - 64bit have no problem atomically reading u64 values, irq safe.
212 					     unsigned int start)  in u64_stats_fetch_retry_irq()  argument
217 	return __u64_stats_fetch_retry(syncp, start);  in u64_stats_fetch_retry_irq()