This commit switches from a direct test of SRCU_READ_FLAVOR_LITE to a new
SRCU_READ_FLAVOR_SLOWGP macro to check for substituting synchronize_rcu()
for smp_mb() in SRCU grace periods. Right now, SRCU_READ_FLAVOR_SLOWGP
is exactly SRCU_READ_FLAVOR_LITE, but the addition of the _fast() flavor
of SRCU will change that.
Signed-off-by: Paul E. McKenney <paul...@kernel.org>
Cc: Alexei Starovoitov <a...@kernel.org>
Cc: Andrii Nakryiko <and...@kernel.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Kent Overstreet <kent.overstr...@linux.dev>
Cc: <b...@vger.kernel.org>
---
include/linux/srcu.h | 3 +++
kernel/rcu/srcutree.c | 6 +++---
2 files changed, 6 insertions(+), 3 deletions(-)
diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index ca00b9af7c23..505f5bdce444 100644
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -49,6 +49,9 @@ int init_srcu_struct(struct srcu_struct *ssp);
#define SRCU_READ_FLAVOR_LITE 0x4 // srcu_read_lock_lite().
#define SRCU_READ_FLAVOR_ALL (SRCU_READ_FLAVOR_NORMAL | SRCU_READ_FLAVOR_NMI
| \
SRCU_READ_FLAVOR_LITE) // All of the above.
+#define SRCU_READ_FLAVOR_SLOWGP SRCU_READ_FLAVOR_LITE
+ // Flavors requiring
synchronize_rcu()
+ // instead of smp_mb().
#ifdef CONFIG_TINY_SRCU
#include <linux/srcutiny.h>
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index 46e4cdaa1786..973e49d04f4f 100644
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -449,7 +449,7 @@ static bool srcu_readers_lock_idx(struct srcu_struct *ssp,
int idx, bool gp, uns
}
WARN_ONCE(IS_ENABLED(CONFIG_PROVE_RCU) && (mask & (mask - 1)),
"Mixed reader flavors for srcu_struct at %ps.\n", ssp);
- if (mask & SRCU_READ_FLAVOR_LITE && !gp)
+ if (mask & SRCU_READ_FLAVOR_SLOWGP && !gp)
return false;
return sum == unlocks;
}
@@ -487,7 +487,7 @@ static bool srcu_readers_active_idx_check(struct
srcu_struct *ssp, int idx)
unsigned long unlocks;
unlocks = srcu_readers_unlock_idx(ssp, idx, &rdm);
- did_gp = !!(rdm & SRCU_READ_FLAVOR_LITE);
+ did_gp = !!(rdm & SRCU_READ_FLAVOR_SLOWGP);
/*
* Make sure that a lock is always counted if the corresponding
@@ -1205,7 +1205,7 @@ static bool srcu_should_expedite(struct srcu_struct *ssp)
check_init_srcu_struct(ssp);
/* If _lite() readers, don't do unsolicited expediting. */
- if (this_cpu_read(ssp->sda->srcu_reader_flavor) & SRCU_READ_FLAVOR_LITE)
+ if (this_cpu_read(ssp->sda->srcu_reader_flavor) &
SRCU_READ_FLAVOR_SLOWGP)
return false;
/* If the local srcu_data structure has callbacks, not idle. */
sdp = raw_cpu_ptr(ssp->sda);
--
2.40.1
