[dpdk-dev] [PATCH v1 1/7] power_intrinsics: allow monitor checks inversion

[Anatoly Burakov]

Previously, the semantics of power monitor were such that we were
checking current value against the expected value, and if they matched,
then the sleep was aborted. This is somewhat inflexible, because it only
allowed us to check for a specific value.

This commit adds an option to reverse the check, so that we can have
monitor sleep aborted if the expected value *doesn't* match what's in
memory. This allows us to both implement all currently implemented
driver code, as well as support more use cases which don't easily map to
previous semantics (such as waiting on writes to AF_XDP counter value).

Since the old behavior is the default, no need to adjust existing
implementations.

Signed-off-by: Anatoly Burakov <anatoly.burakov at intel.com>
---
 lib/eal/include/generic/rte_power_intrinsics.h | 4 ++++
 lib/eal/x86/rte_power_intrinsics.c             | 5 ++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/lib/eal/include/generic/rte_power_intrinsics.h b/lib/eal/include/generic/rte_power_intrinsics.h
index dddca3d41c..1006c2edfc 100644
--- a/lib/eal/include/generic/rte_power_intrinsics.h
+++ b/lib/eal/include/generic/rte_power_intrinsics.h
@@ -31,6 +31,10 @@ struct rte_power_monitor_cond {
 	                  *   4, or 8. Supplying any other value will result in
 	                  *   an error.
 	                  */
+	uint8_t invert;  /**< Invert check for expected value (e.g. instead of
+	                  *   checking if `val` matches something, check if
+	                  *   `val` *doesn't* match a particular value)
+	                  */
 };
 
 /**
diff --git a/lib/eal/x86/rte_power_intrinsics.c b/lib/eal/x86/rte_power_intrinsics.c
index 39ea9fdecd..5d944e9aa4 100644
--- a/lib/eal/x86/rte_power_intrinsics.c
+++ b/lib/eal/x86/rte_power_intrinsics.c
@@ -117,7 +117,10 @@ rte_power_monitor(const struct rte_power_monitor_cond *pmc,
 		const uint64_t masked = cur_value & pmc->mask;
 
 		/* if the masked value is already matching, abort */
-		if (masked == pmc->val)
+		if (!pmc->invert && masked == pmc->val)
+			goto end;
+		/* same, but for inverse check */
+		if (pmc->invert && masked != pmc->val)
 			goto end;
 	}
 
-- 
2.25.1