diff options
Diffstat (limited to 'kernel/rcu/srcutree.c')
| -rw-r--r-- | kernel/rcu/srcutree.c | 36 |
1 files changed, 27 insertions, 9 deletions
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index fec608f69962..155c430c6a73 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -107,6 +107,18 @@ static void init_srcu_struct_data(struct srcu_struct *ssp) } } +/* Invalid seq state, used during snp node initialization */ +#define SRCU_SNP_INIT_SEQ 0x2 + +/* + * Check whether sequence number corresponding to snp node, + * is invalid. + */ +static inline bool srcu_invl_snp_seq(unsigned long s) +{ + return rcu_seq_state(s) == SRCU_SNP_INIT_SEQ; +} + /* * Allocated and initialize SRCU combining tree. Returns @true if * allocation succeeded and @false otherwise. @@ -139,10 +151,10 @@ static bool init_srcu_struct_nodes(struct srcu_struct *ssp) WARN_ON_ONCE(ARRAY_SIZE(snp->srcu_have_cbs) != ARRAY_SIZE(snp->srcu_data_have_cbs)); for (i = 0; i < ARRAY_SIZE(snp->srcu_have_cbs); i++) { - snp->srcu_have_cbs[i] = 0; + snp->srcu_have_cbs[i] = SRCU_SNP_INIT_SEQ; snp->srcu_data_have_cbs[i] = 0; } - snp->srcu_gp_seq_needed_exp = 0; + snp->srcu_gp_seq_needed_exp = SRCU_SNP_INIT_SEQ; snp->grplo = -1; snp->grphi = -1; if (snp == &ssp->node[0]) { @@ -386,8 +398,7 @@ static bool srcu_readers_active(struct srcu_struct *ssp) */ static unsigned long srcu_get_delay(struct srcu_struct *ssp) { - if (ULONG_CMP_LT(READ_ONCE(ssp->srcu_gp_seq), - READ_ONCE(ssp->srcu_gp_seq_needed_exp))) + if (ULONG_CMP_LT(READ_ONCE(ssp->srcu_gp_seq), READ_ONCE(ssp->srcu_gp_seq_needed_exp))) return 0; return SRCU_INTERVAL; } @@ -561,6 +572,7 @@ static void srcu_gp_end(struct srcu_struct *ssp) int idx; unsigned long mask; struct srcu_data *sdp; + unsigned long sgsne; struct srcu_node *snp; int ss_state; @@ -594,7 +606,8 @@ static void srcu_gp_end(struct srcu_struct *ssp) cbs = snp->srcu_have_cbs[idx] == gpseq; snp->srcu_have_cbs[idx] = gpseq; rcu_seq_set_state(&snp->srcu_have_cbs[idx], 1); - if (ULONG_CMP_LT(snp->srcu_gp_seq_needed_exp, gpseq)) + sgsne = snp->srcu_gp_seq_needed_exp; + if (srcu_invl_snp_seq(sgsne) || ULONG_CMP_LT(sgsne, gpseq)) WRITE_ONCE(snp->srcu_gp_seq_needed_exp, gpseq); mask = snp->srcu_data_have_cbs[idx]; snp->srcu_data_have_cbs[idx] = 0; @@ -652,14 +665,17 @@ static void srcu_funnel_exp_start(struct srcu_struct *ssp, struct srcu_node *snp unsigned long s) { unsigned long flags; + unsigned long sgsne; if (snp) for (; snp != NULL; snp = snp->srcu_parent) { + sgsne = READ_ONCE(snp->srcu_gp_seq_needed_exp); if (rcu_seq_done(&ssp->srcu_gp_seq, s) || - ULONG_CMP_GE(READ_ONCE(snp->srcu_gp_seq_needed_exp), s)) + (!srcu_invl_snp_seq(sgsne) && ULONG_CMP_GE(sgsne, s))) return; spin_lock_irqsave_rcu_node(snp, flags); - if (ULONG_CMP_GE(snp->srcu_gp_seq_needed_exp, s)) { + sgsne = snp->srcu_gp_seq_needed_exp; + if (!srcu_invl_snp_seq(sgsne) && ULONG_CMP_GE(sgsne, s)) { spin_unlock_irqrestore_rcu_node(snp, flags); return; } @@ -687,6 +703,7 @@ static void srcu_funnel_gp_start(struct srcu_struct *ssp, struct srcu_data *sdp, { unsigned long flags; int idx = rcu_seq_ctr(s) % ARRAY_SIZE(sdp->mynode->srcu_have_cbs); + unsigned long sgsne; struct srcu_node *snp; struct srcu_node *snp_leaf = smp_load_acquire(&sdp->mynode); unsigned long snp_seq; @@ -698,7 +715,7 @@ static void srcu_funnel_gp_start(struct srcu_struct *ssp, struct srcu_data *sdp, return; /* GP already done and CBs recorded. */ spin_lock_irqsave_rcu_node(snp, flags); snp_seq = snp->srcu_have_cbs[idx]; - if (ULONG_CMP_GE(snp_seq, s)) { + if (!srcu_invl_snp_seq(snp_seq) && ULONG_CMP_GE(snp_seq, s)) { if (snp == snp_leaf && snp_seq == s) snp->srcu_data_have_cbs[idx] |= sdp->grpmask; spin_unlock_irqrestore_rcu_node(snp, flags); @@ -713,7 +730,8 @@ static void srcu_funnel_gp_start(struct srcu_struct *ssp, struct srcu_data *sdp, snp->srcu_have_cbs[idx] = s; if (snp == snp_leaf) snp->srcu_data_have_cbs[idx] |= sdp->grpmask; - if (!do_norm && ULONG_CMP_LT(snp->srcu_gp_seq_needed_exp, s)) + sgsne = snp->srcu_gp_seq_needed_exp; + if (!do_norm && (srcu_invl_snp_seq(sgsne) || ULONG_CMP_LT(sgsne, s))) WRITE_ONCE(snp->srcu_gp_seq_needed_exp, s); spin_unlock_irqrestore_rcu_node(snp, flags); } |