diff options
| -rw-r--r-- | include/linux/srcu.h | 12 | ||||
| -rw-r--r-- | include/linux/srcutree.h | 5 | ||||
| -rw-r--r-- | kernel/rcu/srcutree.c | 38 |
3 files changed, 43 insertions, 12 deletions
diff --git a/include/linux/srcu.h b/include/linux/srcu.h index 4fac088072c3..1a7840c1b87a 100644 --- a/include/linux/srcu.h +++ b/include/linux/srcu.h @@ -65,14 +65,14 @@ unsigned long start_poll_synchronize_srcu(struct srcu_struct *ssp); bool poll_state_synchronize_srcu(struct srcu_struct *ssp, unsigned long cookie); #ifdef CONFIG_NEED_SRCU_NMI_SAFE -int __srcu_read_lock_nmisafe(struct srcu_struct *ssp) __acquires(ssp); -void __srcu_read_unlock_nmisafe(struct srcu_struct *ssp, int idx) __releases(ssp); +int __srcu_read_lock_nmisafe(struct srcu_struct *ssp, bool chknmisafe) __acquires(ssp); +void __srcu_read_unlock_nmisafe(struct srcu_struct *ssp, int idx, bool chknmisafe) __releases(ssp); #else -static inline int __srcu_read_lock_nmisafe(struct srcu_struct *ssp) +static inline int __srcu_read_lock_nmisafe(struct srcu_struct *ssp, bool chknmisafe) { return __srcu_read_lock(ssp); } -static inline void __srcu_read_unlock_nmisafe(struct srcu_struct *ssp, int idx) +static inline void __srcu_read_unlock_nmisafe(struct srcu_struct *ssp, int idx, bool chknmisafe) { __srcu_read_unlock(ssp, idx); } @@ -192,7 +192,7 @@ static inline int srcu_read_lock_nmisafe(struct srcu_struct *ssp) __acquires(ssp int retval; if (IS_ENABLED(CONFIG_NEED_SRCU_NMI_SAFE)) - retval = __srcu_read_lock_nmisafe(ssp); + retval = __srcu_read_lock_nmisafe(ssp, true); else retval = __srcu_read_lock(ssp); rcu_lock_acquire(&(ssp)->dep_map); @@ -237,7 +237,7 @@ static inline void srcu_read_unlock_nmisafe(struct srcu_struct *ssp, int idx) WARN_ON_ONCE(idx & ~0x1); rcu_lock_release(&(ssp)->dep_map); if (IS_ENABLED(CONFIG_NEED_SRCU_NMI_SAFE)) - __srcu_read_unlock_nmisafe(ssp, idx); + __srcu_read_unlock_nmisafe(ssp, idx, true); else __srcu_read_unlock(ssp, idx); } diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h index 0c4eca07d78d..1ef8f2a4884f 100644 --- a/include/linux/srcutree.h +++ b/include/linux/srcutree.h @@ -25,6 +25,7 @@ struct srcu_data { /* Read-side state. */ atomic_long_t srcu_lock_count[2]; /* Locks per CPU. */ atomic_long_t srcu_unlock_count[2]; /* Unlocks per CPU. */ + int srcu_nmi_safety; /* NMI-safe srcu_struct structure? */ /* Update-side state. */ spinlock_t __private lock ____cacheline_internodealigned_in_smp; @@ -42,6 +43,10 @@ struct srcu_data { struct srcu_struct *ssp; }; +#define SRCU_NMI_UNKNOWN 0x0 +#define SRCU_NMI_NMI_UNSAFE 0x1 +#define SRCU_NMI_NMI_SAFE 0x2 + /* * Node in SRCU combining tree, similar in function to rcu_data. */ diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 32a94b254d29..30575864fcfa 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -627,6 +627,26 @@ void cleanup_srcu_struct(struct srcu_struct *ssp) EXPORT_SYMBOL_GPL(cleanup_srcu_struct); /* + * Check for consistent NMI safety. + */ +static void srcu_check_nmi_safety(struct srcu_struct *ssp, bool nmi_safe) +{ + int nmi_safe_mask = 1 << nmi_safe; + int old_nmi_safe_mask; + struct srcu_data *sdp; + + if (!IS_ENABLED(CONFIG_PROVE_RCU)) + return; + sdp = raw_cpu_ptr(ssp->sda); + old_nmi_safe_mask = READ_ONCE(sdp->srcu_nmi_safety); + if (!old_nmi_safe_mask) { + WRITE_ONCE(sdp->srcu_nmi_safety, nmi_safe_mask); + return; + } + WARN_ONCE(old_nmi_safe_mask != nmi_safe_mask, "CPU %d old state %d new state %d\n", sdp->cpu, old_nmi_safe_mask, nmi_safe_mask); +} + +/* * Counts the new reader in the appropriate per-CPU element of the * srcu_struct. * Returns an index that must be passed to the matching srcu_read_unlock(). @@ -638,6 +658,7 @@ int __srcu_read_lock(struct srcu_struct *ssp) idx = READ_ONCE(ssp->srcu_idx) & 0x1; this_cpu_inc(ssp->sda->srcu_lock_count[idx].counter); smp_mb(); /* B */ /* Avoid leaking the critical section. */ + srcu_check_nmi_safety(ssp, false); return idx; } EXPORT_SYMBOL_GPL(__srcu_read_lock); @@ -651,6 +672,7 @@ void __srcu_read_unlock(struct srcu_struct *ssp, int idx) { smp_mb(); /* C */ /* Avoid leaking the critical section. */ this_cpu_inc(ssp->sda->srcu_unlock_count[idx].counter); + srcu_check_nmi_safety(ssp, false); } EXPORT_SYMBOL_GPL(__srcu_read_unlock); @@ -661,7 +683,7 @@ EXPORT_SYMBOL_GPL(__srcu_read_unlock); * srcu_struct, but in an NMI-safe manner using RMW atomics. * Returns an index that must be passed to the matching srcu_read_unlock(). */ -int __srcu_read_lock_nmisafe(struct srcu_struct *ssp) +int __srcu_read_lock_nmisafe(struct srcu_struct *ssp, bool chknmisafe) { int idx; struct srcu_data *sdp = raw_cpu_ptr(ssp->sda); @@ -669,6 +691,8 @@ int __srcu_read_lock_nmisafe(struct srcu_struct *ssp) idx = READ_ONCE(ssp->srcu_idx) & 0x1; atomic_long_inc(&sdp->srcu_lock_count[idx]); smp_mb__after_atomic(); /* B */ /* Avoid leaking the critical section. */ + if (chknmisafe) + srcu_check_nmi_safety(ssp, true); return idx; } EXPORT_SYMBOL_GPL(__srcu_read_lock_nmisafe); @@ -678,12 +702,14 @@ EXPORT_SYMBOL_GPL(__srcu_read_lock_nmisafe); * element of the srcu_struct. Note that this may well be a different * CPU than that which was incremented by the corresponding srcu_read_lock(). */ -void __srcu_read_unlock_nmisafe(struct srcu_struct *ssp, int idx) +void __srcu_read_unlock_nmisafe(struct srcu_struct *ssp, int idx, bool chknmisafe) { struct srcu_data *sdp = raw_cpu_ptr(ssp->sda); smp_mb__before_atomic(); /* C */ /* Avoid leaking the critical section. */ atomic_long_inc(&sdp->srcu_unlock_count[idx]); + if (chknmisafe) + srcu_check_nmi_safety(ssp, true); } EXPORT_SYMBOL_GPL(__srcu_read_unlock_nmisafe); @@ -1125,7 +1151,7 @@ static unsigned long srcu_gp_start_if_needed(struct srcu_struct *ssp, int ss_state; check_init_srcu_struct(ssp); - idx = __srcu_read_lock_nmisafe(ssp); + idx = __srcu_read_lock_nmisafe(ssp, false); ss_state = smp_load_acquire(&ssp->srcu_size_state); if (ss_state < SRCU_SIZE_WAIT_CALL) sdp = per_cpu_ptr(ssp->sda, 0); @@ -1158,7 +1184,7 @@ static unsigned long srcu_gp_start_if_needed(struct srcu_struct *ssp, srcu_funnel_gp_start(ssp, sdp, s, do_norm); else if (needexp) srcu_funnel_exp_start(ssp, sdp_mynode, s); - __srcu_read_unlock_nmisafe(ssp, idx); + __srcu_read_unlock_nmisafe(ssp, idx, false); return s; } @@ -1462,13 +1488,13 @@ void srcu_barrier(struct srcu_struct *ssp) /* Initial count prevents reaching zero until all CBs are posted. */ atomic_set(&ssp->srcu_barrier_cpu_cnt, 1); - idx = __srcu_read_lock_nmisafe(ssp); + idx = __srcu_read_lock_nmisafe(ssp, false); if (smp_load_acquire(&ssp->srcu_size_state) < SRCU_SIZE_WAIT_BARRIER) srcu_barrier_one_cpu(ssp, per_cpu_ptr(ssp->sda, 0)); else for_each_possible_cpu(cpu) srcu_barrier_one_cpu(ssp, per_cpu_ptr(ssp->sda, cpu)); - __srcu_read_unlock_nmisafe(ssp, idx); + __srcu_read_unlock_nmisafe(ssp, idx, false); /* Remove the initial count, at which point reaching zero can happen. */ if (atomic_dec_and_test(&ssp->srcu_barrier_cpu_cnt)) |