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| author |   Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2018-04-25 13:01:25 -0700 |
|---|---|---|
| committer |   Paul E. McKenney <paulmck@linux.ibm.com> | 2018-11-08 21:54:14 -0800 |
| commit | 0607ba8403c4cdb253f8c5200ecf654dfb7790cc (patch) | |
| tree | 1c980c7df600c90717f87172df7d9259a233a87a /kernel/rcu | |
| parent | srcu: Fix kernel-doc missing notation (diff) | |
| download | linux-dev-0607ba8403c4cdb253f8c5200ecf654dfb7790cc.tar.xz linux-dev-0607ba8403c4cdb253f8c5200ecf654dfb7790cc.zip | |
srcu: Prevent __call_srcu() counter wrap with read-side critical section
Ever since cdf7abc4610a ("srcu: Allow use of Tiny/Tree SRCU from
both process and interrupt context"), it has been permissible
to use SRCU read-side critical sections in interrupt context.
This allows __call_srcu() to use SRCU read-side critical sections to
prevent a new SRCU grace period from ending before the call to either
srcu_funnel_gp_start() or srcu_funnel_exp_start completes, thus preventing
SRCU grace-period counter overflow during that time.
Note that this does not permit removal of the counter-wrap checks in
srcu_gp_end(). These check are necessary to handle the case where
a given CPU does not interact at all with SRCU for an extended time
period.
This commit therefore adds an SRCU read-side critical section to
__call_srcu() in order to prevent grace period counter wrap during
the funnel-locking process.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/srcutree.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index a8846ed7f352..60f3236beaf7 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -858,6 +858,7 @@ void __call_srcu(struct srcu_struct *sp, struct rcu_head *rhp, rcu_callback_t func, bool do_norm) { unsigned long flags; + int idx; bool needexp = false; bool needgp = false; unsigned long s; @@ -871,6 +872,7 @@ void __call_srcu(struct srcu_struct *sp, struct rcu_head *rhp, return; } rhp->func = func; + idx = srcu_read_lock(sp); local_irq_save(flags); sdp = this_cpu_ptr(sp->sda); spin_lock_rcu_node(sdp); @@ -892,6 +894,7 @@ void __call_srcu(struct srcu_struct *sp, struct rcu_head *rhp, srcu_funnel_gp_start(sp, sdp, s, do_norm); else if (needexp) srcu_funnel_exp_start(sp, sdp->mynode, s); + srcu_read_unlock(sp, idx); } /** |