Commit f4bde41d authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Boqun Feng
Browse files

srcu: Pull pointer-to-integer conversion into __srcu_ptr_to_ctr() 



This commit abstracts the srcu_read_lock*() pointer-to-integer conversion
into a new __srcu_ptr_to_ctr().  This will be used in rcutorture for
testing an srcu_read_lock_fast() that returns a pointer rather than
an integer.

Signed-off-by: default avatarPaul 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: default avatarBoqun Feng <boqun.feng@gmail.com>
parent 4d86b1e7

include/linux/srcutree.h

+8 −1
Original line number Diff line number Diff line
@@ -211,6 +211,13 @@ void synchronize_srcu_expedited(struct srcu_struct *ssp); 
void srcu_barrier(struct srcu_struct *ssp);

void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf);



// Converts a per-CPU pointer to an ->srcu_ctrs[] array element to that

// element's index.

static inline bool __srcu_ptr_to_ctr(struct srcu_struct *ssp, struct srcu_ctr __percpu *scpp)

{

	return scpp - &ssp->sda->srcu_ctrs[0];

}



/*

 * Counts the new reader in the appropriate per-CPU element of the

 * srcu_struct.  Returns an index that must be passed to the matching
@@ -228,7 +235,7 @@ static inline int __srcu_read_lock_lite(struct srcu_struct *ssp) 
	RCU_LOCKDEP_WARN(!rcu_is_watching(), "RCU must be watching srcu_read_lock_lite().");

	this_cpu_inc(scp->srcu_locks.counter); /* Y */

	barrier(); /* Avoid leaking the critical section. */

	return scp - &ssp->sda->srcu_ctrs[0];

	return __srcu_ptr_to_ctr(ssp, scp);

}



/*

kernel/rcu/srcutree.c

+2 −2
Original line number Diff line number Diff line
@@ -753,7 +753,7 @@ int __srcu_read_lock(struct srcu_struct *ssp) 


	this_cpu_inc(scp->srcu_locks.counter);

	smp_mb(); /* B */  /* Avoid leaking the critical section. */

	return scp - &ssp->sda->srcu_ctrs[0];

	return __srcu_ptr_to_ctr(ssp, scp);

}

EXPORT_SYMBOL_GPL(__srcu_read_lock);
@@ -783,7 +783,7 @@ int __srcu_read_lock_nmisafe(struct srcu_struct *ssp) 


	atomic_long_inc(&scp->srcu_locks);

	smp_mb__after_atomic(); /* B */  /* Avoid leaking the critical section. */

	return scpp - &ssp->sda->srcu_ctrs[0];

	return __srcu_ptr_to_ctr(ssp, scpp);

}

EXPORT_SYMBOL_GPL(__srcu_read_lock_nmisafe);