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McKenney wrote: > This commit changes a few "cpuc" variables to "sdp" to align wiht usage > elsewhere. > s/wiht/with/ This commit is doing a lot more than renaming "cpuc". - Neeraj > Signed-off-by: Paul E. McKenney > Cc: Alexei Starovoitov > Cc: Andrii Nakryiko > Cc: Peter Zijlstra > Cc: Kent Overstreet > Cc: > --- > include/linux/srcu.h | 35 ++++++++++++++++++---------------- > include/linux/srcutree.h | 4 ++++ > kernel/rcu/srcutree.c | 41 ++++++++++++++++++++-------------------- > 3 files changed, 44 insertions(+), 36 deletions(-) > > diff --git a/include/linux/srcu.h b/include/linux/srcu.h > index 06728ef6f32a4..84daaa33ea0ab 100644 > --- a/include/linux/srcu.h > +++ b/include/linux/srcu.h > @@ -176,10 +176,6 @@ static inline int srcu_read_lock_held(const struct srcu_struct *ssp) > > #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */ > > -#define SRCU_NMI_UNKNOWN 0x0 > -#define SRCU_NMI_UNSAFE 0x1 > -#define SRCU_NMI_SAFE 0x2 > - > #if defined(CONFIG_PROVE_RCU) && defined(CONFIG_TREE_SRCU) > void srcu_check_read_flavor(struct srcu_struct *ssp, int read_flavor); > #else > @@ -235,16 +231,19 @@ static inline void srcu_check_read_flavor(struct srcu_struct *ssp, int read_flav > * a mutex that is held elsewhere while calling synchronize_srcu() or > * synchronize_srcu_expedited(). > * > - * Note that srcu_read_lock() and the matching srcu_read_unlock() must > - * occur in the same context, for example, it is illegal to invoke > - * srcu_read_unlock() in an irq handler if the matching srcu_read_lock() > - * was invoked in process context. > + * The return value from srcu_read_lock() must be passed unaltered > + * to the matching srcu_read_unlock(). Note that srcu_read_lock() and > + * the matching srcu_read_unlock() must occur in the same context, for > + * example, it is illegal to invoke srcu_read_unlock() in an irq handler > + * if the matching srcu_read_lock() was invoked in process context. Or, > + * for that matter to invoke srcu_read_unlock() from one task and the > + * matching srcu_read_lock() from another. > */ > static inline int srcu_read_lock(struct srcu_struct *ssp) __acquires(ssp) > { > int retval; > > - srcu_check_read_flavor(ssp, false); > + srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_NORMAL); > retval = __srcu_read_lock(ssp); > srcu_lock_acquire(&ssp->dep_map); > return retval; > @@ -256,12 +255,16 @@ static inline int srcu_read_lock(struct srcu_struct *ssp) __acquires(ssp) > * > * Enter an SRCU read-side critical section, but in an NMI-safe manner. > * See srcu_read_lock() for more information. > + * > + * If srcu_read_lock_nmisafe() is ever used on an srcu_struct structure, > + * then none of the other flavors may be used, whether before, during, > + * or after. > */ > static inline int srcu_read_lock_nmisafe(struct srcu_struct *ssp) __acquires(ssp) > { > int retval; > > - srcu_check_read_flavor(ssp, true); > + srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_NMI); > retval = __srcu_read_lock_nmisafe(ssp); > rcu_try_lock_acquire(&ssp->dep_map); > return retval; > @@ -273,7 +276,7 @@ srcu_read_lock_notrace(struct srcu_struct *ssp) __acquires(ssp) > { > int retval; > > - srcu_check_read_flavor(ssp, false); > + srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_NORMAL); > retval = __srcu_read_lock(ssp); > return retval; > } > @@ -302,7 +305,7 @@ srcu_read_lock_notrace(struct srcu_struct *ssp) __acquires(ssp) > static inline int srcu_down_read(struct srcu_struct *ssp) __acquires(ssp) > { > WARN_ON_ONCE(in_nmi()); > - srcu_check_read_flavor(ssp, false); > + srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_NORMAL); > return __srcu_read_lock(ssp); > } > > @@ -317,7 +320,7 @@ static inline void srcu_read_unlock(struct srcu_struct *ssp, int idx) > __releases(ssp) > { > WARN_ON_ONCE(idx & ~0x1); > - srcu_check_read_flavor(ssp, false); > + srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_NORMAL); > srcu_lock_release(&ssp->dep_map); > __srcu_read_unlock(ssp, idx); > } > @@ -333,7 +336,7 @@ static inline void srcu_read_unlock_nmisafe(struct srcu_struct *ssp, int idx) > __releases(ssp) > { > WARN_ON_ONCE(idx & ~0x1); > - srcu_check_read_flavor(ssp, true); > + srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_NMI); > rcu_lock_release(&ssp->dep_map); > __srcu_read_unlock_nmisafe(ssp, idx); > } > @@ -342,7 +345,7 @@ static inline void srcu_read_unlock_nmisafe(struct srcu_struct *ssp, int idx) > static inline notrace void > srcu_read_unlock_notrace(struct srcu_struct *ssp, int idx) __releases(ssp) > { > - srcu_check_read_flavor(ssp, false); > + srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_NORMAL); > __srcu_read_unlock(ssp, idx); > } > > @@ -359,7 +362,7 @@ static inline void srcu_up_read(struct srcu_struct *ssp, int idx) > { > WARN_ON_ONCE(idx & ~0x1); > WARN_ON_ONCE(in_nmi()); > - srcu_check_read_flavor(ssp, false); > + srcu_check_read_flavor(ssp, SRCU_READ_FLAVOR_NORMAL); > __srcu_read_unlock(ssp, idx); > } > > diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h > index ab7d8d215b84b..79ad809c7f035 100644 > --- a/include/linux/srcutree.h > +++ b/include/linux/srcutree.h > @@ -43,6 +43,10 @@ struct srcu_data { > struct srcu_struct *ssp; > }; > > +/* Values for ->srcu_reader_flavor. */ > +#define SRCU_READ_FLAVOR_NORMAL 0x1 // srcu_read_lock(). > +#define SRCU_READ_FLAVOR_NMI 0x2 // srcu_read_lock_nmisafe(). > + > /* > * Node in SRCU combining tree, similar in function to rcu_data. > */ > diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c > index abe55777c4335..4c51be484b48a 100644 > --- a/kernel/rcu/srcutree.c > +++ b/kernel/rcu/srcutree.c > @@ -438,9 +438,9 @@ static unsigned long srcu_readers_lock_idx(struct srcu_struct *ssp, int idx) > unsigned long sum = 0; > > for_each_possible_cpu(cpu) { > - struct srcu_data *cpuc = per_cpu_ptr(ssp->sda, cpu); > + struct srcu_data *sdp = per_cpu_ptr(ssp->sda, cpu); > > - sum += atomic_long_read(&cpuc->srcu_lock_count[idx]); > + sum += atomic_long_read(&sdp->srcu_lock_count[idx]); > } > return sum; > } > @@ -456,14 +456,14 @@ static unsigned long srcu_readers_unlock_idx(struct srcu_struct *ssp, int idx) > unsigned long sum = 0; > > for_each_possible_cpu(cpu) { > - struct srcu_data *cpuc = per_cpu_ptr(ssp->sda, cpu); > + struct srcu_data *sdp = per_cpu_ptr(ssp->sda, cpu); > > - sum += atomic_long_read(&cpuc->srcu_unlock_count[idx]); > + sum += atomic_long_read(&sdp->srcu_unlock_count[idx]); > if (IS_ENABLED(CONFIG_PROVE_RCU)) > - mask = mask | READ_ONCE(cpuc->srcu_reader_flavor); > + mask = mask | READ_ONCE(sdp->srcu_reader_flavor); > } > WARN_ONCE(IS_ENABLED(CONFIG_PROVE_RCU) && (mask & (mask - 1)), > - "Mixed NMI-safe readers for srcu_struct at %ps.\n", ssp); > + "Mixed reader flavors for srcu_struct at %ps.\n", ssp); > return sum; > } > > @@ -564,12 +564,12 @@ static bool srcu_readers_active(struct srcu_struct *ssp) > unsigned long sum = 0; > > for_each_possible_cpu(cpu) { > - struct srcu_data *cpuc = per_cpu_ptr(ssp->sda, cpu); > + struct srcu_data *sdp = per_cpu_ptr(ssp->sda, cpu); > > - sum += atomic_long_read(&cpuc->srcu_lock_count[0]); > - sum += atomic_long_read(&cpuc->srcu_lock_count[1]); > - sum -= atomic_long_read(&cpuc->srcu_unlock_count[0]); > - sum -= atomic_long_read(&cpuc->srcu_unlock_count[1]); > + sum += atomic_long_read(&sdp->srcu_lock_count[0]); > + sum += atomic_long_read(&sdp->srcu_lock_count[1]); > + sum -= atomic_long_read(&sdp->srcu_unlock_count[0]); > + sum -= atomic_long_read(&sdp->srcu_unlock_count[1]); > } > return sum; > } > @@ -703,20 +703,21 @@ EXPORT_SYMBOL_GPL(cleanup_srcu_struct); > */ > void srcu_check_read_flavor(struct srcu_struct *ssp, int read_flavor) > { > - int reader_flavor_mask = 1 << read_flavor; > - int old_reader_flavor_mask; > + int old_read_flavor; > struct srcu_data *sdp; > > - /* NMI-unsafe use in NMI is a bad sign */ > - WARN_ON_ONCE(!read_flavor && in_nmi()); > + /* NMI-unsafe use in NMI is a bad sign, as is multi-bit read_flavor values. */ > + WARN_ON_ONCE((read_flavor != SRCU_READ_FLAVOR_NMI) && in_nmi()); > + WARN_ON_ONCE(read_flavor & (read_flavor - 1)); > + > sdp = raw_cpu_ptr(ssp->sda); > - old_reader_flavor_mask = READ_ONCE(sdp->srcu_reader_flavor); > - if (!old_reader_flavor_mask) { > - old_reader_flavor_mask = cmpxchg(&sdp->srcu_reader_flavor, 0, reader_flavor_mask); > - if (!old_reader_flavor_mask) > + old_read_flavor = READ_ONCE(sdp->srcu_reader_flavor); > + if (!old_read_flavor) { > + old_read_flavor = cmpxchg(&sdp->srcu_reader_flavor, 0, read_flavor); > + if (!old_read_flavor) > return; > } > - WARN_ONCE(old_reader_flavor_mask != reader_flavor_mask, "CPU %d old state %d new state %d\n", sdp->cpu, old_reader_flavor_mask, reader_flavor_mask); > + WARN_ONCE(old_read_flavor != read_flavor, "CPU %d old state %d new state %d\n", sdp->cpu, old_read_flavor, read_flavor); > } > EXPORT_SYMBOL_GPL(srcu_check_read_flavor); > #endif /* CONFIG_PROVE_RCU */