Fixes: 0e60020d2a ("proc connector: take number of listeners and per-cpu
conters from VE")
Signed-off-by: Alexander Mikhalitsyn <[email protected]>
---
drivers/connector/cn_proc.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/drivers/connector/cn_proc.c b/drivers/connector/cn_proc.c
index 9b63792f0dff..83c068c900cf 100644
--- a/drivers/connector/cn_proc.c
+++ b/drivers/connector/cn_proc.c
@@ -63,6 +63,21 @@ static inline void send_msg_ve(struct ve_struct *ve, struct
cn_msg *msg)
{
struct local_event *le_ptr;
+ /*
+ * Our kernel is non-PREEMPT_RT or even non-PREEMPT but
+ * to be on the safe side we need to disable task cpu
+ * migration before calculating this_cpu_ptr.
+ *
+ * Note 1. local_lock implies migrate_disable on PREEMPT_RT
+ * kernels and preempt_disable on PREEMPT kernels.
+ * But we need to have migrations disabled *before*
+ * this_cpu_ptr() call.
+ * It's safe to nest migrate_disable/preempt_disable.
+ * Note 2. yep, local_lock is still needed here because
+ * on PREEMPT_RT kernel it is also implies per-cpu spin_lock
+ * which protects from reentrancy problems.
+ */
+ migrate_disable();
le_ptr = this_cpu_ptr(ve->cn->local_event);
local_lock(&le_ptr->lock);
@@ -78,6 +93,7 @@ static inline void send_msg_ve(struct ve_struct *ve, struct
cn_msg *msg)
cn_netlink_send_ve(ve, msg, 0, CN_IDX_PROC, GFP_NOWAIT);
local_unlock(&le_ptr->lock);
+ migrate_enable();
}
static struct cn_msg *cn_msg_fill(__u8 *buffer, struct ve_struct *ve,
--
2.28.0
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