srcu: Rename srcu_check_read_flavor_lite() to srcu_check_read_flavor_force()

This commit renames the srcu_check_read_flavor_lite() function to
srcu_check_read_flavor_force() and adds a read_flavor argument in order to
support an srcu_read_lock_fast() variant that is to avoid array indexing
in both the lock and unlock primitives.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: <bpf@vger.kernel.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>

diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index f6f779b9d9ff219d92e6d2741cb665d59b76050e..ca00b9af7c2370c4c55db4abfbdb4eada2b327d6 100644 (file)
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -279,7 +279,7 @@ static inline int srcu_read_lock_lite(struct srcu_struct *ssp) __acquires(ssp)
 {
        int retval;
 
-       srcu_check_read_flavor_lite(ssp);
+       srcu_check_read_flavor_force(ssp, SRCU_READ_FLAVOR_LITE);
        retval = __srcu_read_lock_lite(ssp);
        rcu_try_lock_acquire(&ssp->dep_map);
        return retval;

diff --git a/include/linux/srcutiny.h b/include/linux/srcutiny.h
index 1321da803274d00320b1d20a415287239b515575..b347bde1aac29f693061f9dd21fb92edc8102626 100644 (file)
--- a/include/linux/srcutiny.h
+++ b/include/linux/srcutiny.h
@@ -82,7 +82,7 @@ static inline void srcu_barrier(struct srcu_struct *ssp)
 }
 
 #define srcu_check_read_flavor(ssp, read_flavor) do { } while (0)
-#define srcu_check_read_flavor_lite(ssp) do { } while (0)
+#define srcu_check_read_flavor_force(ssp, read_flavor) do { } while (0)
 
 /* Defined here to avoid size increase for non-torture kernels. */
 static inline void srcu_torture_stats_print(struct srcu_struct *ssp,

diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h
index 6b7eba59f384938eafc8e51f933fd18742427f69..e29cc57eac81d08c0cd2bb00550f326cc41a9fd4 100644 (file)
--- a/include/linux/srcutree.h
+++ b/include/linux/srcutree.h
@@ -251,16 +251,18 @@ static inline void __srcu_read_unlock_lite(struct srcu_struct *ssp, int idx)
 
 void __srcu_check_read_flavor(struct srcu_struct *ssp, int read_flavor);
 
-// Record _lite() usage even for CONFIG_PROVE_RCU=n kernels.
-static inline void srcu_check_read_flavor_lite(struct srcu_struct *ssp)
+// Record reader usage even for CONFIG_PROVE_RCU=n kernels.  This is
+// needed only for flavors that require grace-period smp_mb() calls to be
+// promoted to synchronize_rcu().
+static inline void srcu_check_read_flavor_force(struct srcu_struct *ssp, int read_flavor)
 {
        struct srcu_data *sdp = raw_cpu_ptr(ssp->sda);
 
-       if (likely(READ_ONCE(sdp->srcu_reader_flavor) & SRCU_READ_FLAVOR_LITE))
+       if (likely(READ_ONCE(sdp->srcu_reader_flavor) & read_flavor))
                return;
 
        // Note that the cmpxchg() in __srcu_check_read_flavor() is fully ordered.
-       __srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_LITE);
+       __srcu_check_read_flavor(ssp, read_flavor);
 }
 
 // Record non-_lite() usage only for CONFIG_PROVE_RCU=y kernels.