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From: Mike Galbraith <umgwanakikbuti@gmail.com>
Date: Thu, 20 Oct 2016 11:15:22 +0200
Subject: [PATCH 246/351] drivers/zram: Don't disable preemption in
zcomp_stream_get/put()
Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=2ac83a7513fa9bd4761845b295a8caf6dd72668e
In v4.7, the driver switched to percpu compression streams, disabling
preemption via get/put_cpu_ptr(). Use a per-zcomp_strm lock here. We
also have to fix an lock order issue in zram_decompress_page() such
that zs_map_object() nests inside of zcomp_stream_put() as it does in
zram_bvec_write().
Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
[bigeasy: get_locked_var() -> per zcomp_strm lock]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
drivers/block/zram/zcomp.c | 12 ++++++++++--
drivers/block/zram/zcomp.h | 1 +
drivers/block/zram/zram_drv.c | 5 +++--
3 files changed, 14 insertions(+), 4 deletions(-)
diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c
index 4ed0a78fdc09..dd65a27ae2cc 100644
--- a/drivers/block/zram/zcomp.c
+++ b/drivers/block/zram/zcomp.c
@@ -116,12 +116,19 @@ ssize_t zcomp_available_show(const char *comp, char *buf)
struct zcomp_strm *zcomp_stream_get(struct zcomp *comp)
{
- return *get_cpu_ptr(comp->stream);
+ struct zcomp_strm *zstrm;
+
+ zstrm = *this_cpu_ptr(comp->stream);
+ spin_lock(&zstrm->zcomp_lock);
+ return zstrm;
}
void zcomp_stream_put(struct zcomp *comp)
{
- put_cpu_ptr(comp->stream);
+ struct zcomp_strm *zstrm;
+
+ zstrm = *this_cpu_ptr(comp->stream);
+ spin_unlock(&zstrm->zcomp_lock);
}
int zcomp_compress(struct zcomp_strm *zstrm,
@@ -171,6 +178,7 @@ int zcomp_cpu_up_prepare(unsigned int cpu, struct hlist_node *node)
pr_err("Can't allocate a compression stream\n");
return -ENOMEM;
}
+ spin_lock_init(&zstrm->zcomp_lock);
*per_cpu_ptr(comp->stream, cpu) = zstrm;
return 0;
}
diff --git a/drivers/block/zram/zcomp.h b/drivers/block/zram/zcomp.h
index 41c1002a7d7d..d424eafcbf8e 100644
--- a/drivers/block/zram/zcomp.h
+++ b/drivers/block/zram/zcomp.h
@@ -14,6 +14,7 @@ struct zcomp_strm {
/* compression/decompression buffer */
void *buffer;
struct crypto_comp *tfm;
+ spinlock_t zcomp_lock;
};
/* dynamic per-device compression frontend */
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 04e4297f8318..2919ad13bce9 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1028,6 +1028,7 @@ static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index,
unsigned long handle;
unsigned int size;
void *src, *dst;
+ struct zcomp_strm *zstrm;
if (zram_wb_enabled(zram)) {
zram_slot_lock(zram, index);
@@ -1062,6 +1063,7 @@ static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index,
size = zram_get_obj_size(zram, index);
+ zstrm = zcomp_stream_get(zram->comp);
src = zs_map_object(zram->mem_pool, handle, ZS_MM_RO);
if (size == PAGE_SIZE) {
dst = kmap_atomic(page);
@@ -1069,14 +1071,13 @@ static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index,
kunmap_atomic(dst);
ret = 0;
} else {
- struct zcomp_strm *zstrm = zcomp_stream_get(zram->comp);
dst = kmap_atomic(page);
ret = zcomp_decompress(zstrm, src, size, dst);
kunmap_atomic(dst);
- zcomp_stream_put(zram->comp);
}
zs_unmap_object(zram->mem_pool, handle);
+ zcomp_stream_put(zram->comp);
zram_slot_unlock(zram, index);
/* Should NEVER happen. Return bio error if it does. */
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