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

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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: 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>
This commit is contained in:
Paul E. McKenney 2025-01-08 14:31:27 -08:00 committed by Boqun Feng
parent 4d86b1e7e1
commit f4bde41dd1
2 changed files with 10 additions and 3 deletions
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9
include/linux/srcutree.h
View File

@ -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);
}
/*

4
kernel/rcu/srcutree.c
View File

@ -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);