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19f545b6e0
The zcomp driver uses per-CPU compression. The per-CPU data pointer is acquired with get_cpu_ptr() which implicitly disables preemption. It allocates memory inside the preempt disabled region which conflicts with the PREEMPT_RT semantics. Replace the implicit preemption control with an explicit local lock. This allows RT kernels to substitute it with a real per CPU lock, which serializes the access but keeps the code section preemptible. On non RT kernels this maps to preempt_disable() as before, i.e. no functional change. [bigeasy: Use local_lock(), description, drop reordering] Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20200527201119.1692513-8-bigeasy@linutronix.de
43 lines
1.2 KiB
C
43 lines
1.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* Copyright (C) 2014 Sergey Senozhatsky.
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*/
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#ifndef _ZCOMP_H_
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#define _ZCOMP_H_
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#include <linux/local_lock.h>
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struct zcomp_strm {
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/* The members ->buffer and ->tfm are protected by ->lock. */
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local_lock_t lock;
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/* compression/decompression buffer */
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void *buffer;
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struct crypto_comp *tfm;
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};
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/* dynamic per-device compression frontend */
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struct zcomp {
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struct zcomp_strm __percpu *stream;
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const char *name;
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struct hlist_node node;
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};
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int zcomp_cpu_up_prepare(unsigned int cpu, struct hlist_node *node);
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int zcomp_cpu_dead(unsigned int cpu, struct hlist_node *node);
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ssize_t zcomp_available_show(const char *comp, char *buf);
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bool zcomp_available_algorithm(const char *comp);
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struct zcomp *zcomp_create(const char *comp);
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void zcomp_destroy(struct zcomp *comp);
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struct zcomp_strm *zcomp_stream_get(struct zcomp *comp);
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void zcomp_stream_put(struct zcomp *comp);
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int zcomp_compress(struct zcomp_strm *zstrm,
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const void *src, unsigned int *dst_len);
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int zcomp_decompress(struct zcomp_strm *zstrm,
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const void *src, unsigned int src_len, void *dst);
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bool zcomp_set_max_streams(struct zcomp *comp, int num_strm);
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#endif /* _ZCOMP_H_ */
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