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-rw-r--r--debian/patches-rt/0281-drivers-block-zram-Replace-bit-spinlocks-with-rtmute.patch93
1 files changed, 93 insertions, 0 deletions
diff --git a/debian/patches-rt/0281-drivers-block-zram-Replace-bit-spinlocks-with-rtmute.patch b/debian/patches-rt/0281-drivers-block-zram-Replace-bit-spinlocks-with-rtmute.patch
new file mode 100644
index 000000000..4c370a764
--- /dev/null
+++ b/debian/patches-rt/0281-drivers-block-zram-Replace-bit-spinlocks-with-rtmute.patch
@@ -0,0 +1,93 @@
+From b7d25d7dc9f6a1923426c6e235061e825434e4fd Mon Sep 17 00:00:00 2001
+From: Mike Galbraith <umgwanakikbuti@gmail.com>
+Date: Thu, 31 Mar 2016 04:08:28 +0200
+Subject: [PATCH 281/323] drivers/block/zram: Replace bit spinlocks with
+ rtmutex for -rt
+Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.204-rt100.tar.xz
+
+They're nondeterministic, and lead to ___might_sleep() splats in -rt.
+OTOH, they're a lot less wasteful than an rtmutex per page.
+
+Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
+Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+---
+ drivers/block/zram/zram_drv.c | 36 +++++++++++++++++++++++++++++++++++
+ drivers/block/zram/zram_drv.h | 1 +
+ 2 files changed, 37 insertions(+)
+
+diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
+index 0636df6b67db..1a7523cefbe9 100644
+--- a/drivers/block/zram/zram_drv.c
++++ b/drivers/block/zram/zram_drv.c
+@@ -59,6 +59,40 @@ static void zram_free_page(struct zram *zram, size_t index);
+ static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
+ u32 index, int offset, struct bio *bio);
+
++#ifdef CONFIG_PREEMPT_RT
++static void zram_meta_init_table_locks(struct zram *zram, size_t num_pages)
++{
++ size_t index;
++
++ for (index = 0; index < num_pages; index++)
++ spin_lock_init(&zram->table[index].lock);
++}
++
++static int zram_slot_trylock(struct zram *zram, u32 index)
++{
++ int ret;
++
++ ret = spin_trylock(&zram->table[index].lock);
++ if (ret)
++ __set_bit(ZRAM_LOCK, &zram->table[index].flags);
++ return ret;
++}
++
++static void zram_slot_lock(struct zram *zram, u32 index)
++{
++ spin_lock(&zram->table[index].lock);
++ __set_bit(ZRAM_LOCK, &zram->table[index].flags);
++}
++
++static void zram_slot_unlock(struct zram *zram, u32 index)
++{
++ __clear_bit(ZRAM_LOCK, &zram->table[index].flags);
++ spin_unlock(&zram->table[index].lock);
++}
++
++#else
++
++static void zram_meta_init_table_locks(struct zram *zram, size_t num_pages) { }
+
+ static int zram_slot_trylock(struct zram *zram, u32 index)
+ {
+@@ -74,6 +108,7 @@ static void zram_slot_unlock(struct zram *zram, u32 index)
+ {
+ bit_spin_unlock(ZRAM_LOCK, &zram->table[index].flags);
+ }
++#endif
+
+ static inline bool init_done(struct zram *zram)
+ {
+@@ -1165,6 +1200,7 @@ static bool zram_meta_alloc(struct zram *zram, u64 disksize)
+
+ if (!huge_class_size)
+ huge_class_size = zs_huge_class_size(zram->mem_pool);
++ zram_meta_init_table_locks(zram, num_pages);
+ return true;
+ }
+
+diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
+index f2fd46daa760..7e4dd447e1dd 100644
+--- a/drivers/block/zram/zram_drv.h
++++ b/drivers/block/zram/zram_drv.h
+@@ -63,6 +63,7 @@ struct zram_table_entry {
+ unsigned long element;
+ };
+ unsigned long flags;
++ spinlock_t lock;
+ #ifdef CONFIG_ZRAM_MEMORY_TRACKING
+ ktime_t ac_time;
+ #endif
+--
+2.43.0
+