[dpdk-dev] [PATCH v4 1/1] eal/interrupts: add synchronous wrapper around unregister

[Renata Saiakhova <Renata.Saiakhova@ekinops.com>]

Avoid race with unregister interrupt handler if interrupt
source has some active callbacks at the moment, use wrapper
around rte_intr_callback_unregister() to check for -EAGAIN
return value and to loop until rte_intr_callback_unregister()
succeeds.

Signed-off-by: Renata Saiakhova <Renata.Saiakhova@ekinops.com>
Acked-by: Anatoly Burakov <anatoly.burakov@intel.com>
---
 drivers/bus/pci/linux/pci_vfio.c        |  2 +-
 lib/librte_eal/freebsd/eal_interrupts.c | 12 ++++++++++++
 lib/librte_eal/include/rte_interrupts.h | 25 +++++++++++++++++++++++++
 lib/librte_eal/linux/eal_interrupts.c   | 12 ++++++++++++
 lib/librte_eal/version.map              |  1 +
 5 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/drivers/bus/pci/linux/pci_vfio.c b/drivers/bus/pci/linux/pci_vfio.c
index e3f7b6abe..c14f7f8c4 100644
--- a/drivers/bus/pci/linux/pci_vfio.c
+++ b/drivers/bus/pci/linux/pci_vfio.c
@@ -414,7 +414,7 @@ pci_vfio_disable_notifier(struct rte_pci_device *dev)
 		return -1;
 	}
 
-	ret = rte_intr_callback_unregister(&dev->vfio_req_intr_handle,
+	ret = rte_intr_callback_unregister_sync(&dev->vfio_req_intr_handle,
 					   pci_vfio_req_handler,
 					   (void *)&dev->device);
 	if (ret < 0) {
diff --git a/lib/librte_eal/freebsd/eal_interrupts.c b/lib/librte_eal/freebsd/eal_interrupts.c
index 72eeacbc1..86810845f 100644
--- a/lib/librte_eal/freebsd/eal_interrupts.c
+++ b/lib/librte_eal/freebsd/eal_interrupts.c
@@ -345,6 +345,18 @@ rte_intr_callback_unregister(const struct rte_intr_handle *intr_handle,
 	return ret;
 }
 
+int
+rte_intr_callback_unregister_sync(const struct rte_intr_handle *intr_handle,
+		rte_intr_callback_fn cb_fn, void *cb_arg)
+{
+	int ret = 0;
+
+	while ((ret = rte_intr_callback_unregister(intr_handle, cb_fn, cb_arg)) == -EAGAIN)
+		rte_pause();
+
+	return ret;
+}
+
 int
 rte_intr_enable(const struct rte_intr_handle *intr_handle)
 {
diff --git a/lib/librte_eal/include/rte_interrupts.h b/lib/librte_eal/include/rte_interrupts.h
index e3b406abc..cc3bf45d8 100644
--- a/lib/librte_eal/include/rte_interrupts.h
+++ b/lib/librte_eal/include/rte_interrupts.h
@@ -94,6 +94,31 @@ rte_intr_callback_unregister_pending(const struct rte_intr_handle *intr_handle,
 				rte_intr_callback_fn cb_fn, void *cb_arg,
 				rte_intr_unregister_callback_fn ucb_fn);
 
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Loop until rte_intr_callback_unregister() succeeds.
+ * After a call to this function,
+ * the callback provided by the specified interrupt handle is unregistered.
+ *
+ * @param intr_handle
+ *  pointer to the interrupt handle.
+ * @param cb
+ *  callback address.
+ * @param cb_arg
+ *  address of parameter for callback, (void *)-1 means to remove all
+ *  registered which has the same callback address.
+ *
+ * @return
+ *  - On success, return the number of callback entities removed.
+ *  - On failure, a negative value.
+ */
+__rte_experimental
+int
+rte_intr_callback_unregister_sync(const struct rte_intr_handle *intr_handle,
+				rte_intr_callback_fn cb, void *cb_arg);
+
 /**
  * It enables the interrupt for the specified handle.
  *
diff --git a/lib/librte_eal/linux/eal_interrupts.c b/lib/librte_eal/linux/eal_interrupts.c
index 1dd994bd1..22b3b7bcd 100644
--- a/lib/librte_eal/linux/eal_interrupts.c
+++ b/lib/librte_eal/linux/eal_interrupts.c
@@ -662,6 +662,18 @@ rte_intr_callback_unregister(const struct rte_intr_handle *intr_handle,
 	return ret;
 }
 
+int
+rte_intr_callback_unregister_sync(const struct rte_intr_handle *intr_handle,
+			rte_intr_callback_fn cb_fn, void *cb_arg)
+{
+	int ret = 0;
+
+	while ((ret = rte_intr_callback_unregister(intr_handle, cb_fn, cb_arg)) == -EAGAIN)
+		rte_pause();
+
+	return ret;
+}
+
 int
 rte_intr_enable(const struct rte_intr_handle *intr_handle)
 {
diff --git a/lib/librte_eal/version.map b/lib/librte_eal/version.map
index fce90a112..56caa9cc9 100644
--- a/lib/librte_eal/version.map
+++ b/lib/librte_eal/version.map
@@ -318,6 +318,7 @@ EXPERIMENTAL {
 	rte_fbarray_find_rev_biggest_free;
 	rte_fbarray_find_rev_biggest_used;
 	rte_intr_callback_unregister_pending;
+	rte_intr_callback_unregister_sync;
 	rte_realloc_socket;
 
 	# added in 19.08
-- 
2.17.2