Michael Ellerman [off-list ref] writes:

Nathan Lynch [off-list ref] writes:

quoted

The behavior of rtas_ibm_suspend_me_unsafe() is to return -EAGAIN to
the caller until the specified VASI suspend session state makes the
transition from H_VASI_ENABLED to H_VASI_SUSPENDING. In the interest
of separating concerns to prepare for a new implementation of the
join/suspend sequence, extract VASI session polling logic into a
couple of local functions. Waiting for the session state to reach
H_VASI_SUSPENDING before calling rtas_ibm_suspend_me_unsafe() ensures
that we will never get an EAGAIN result necessitating a retry. No
user-visible change in behavior is intended.

Signed-off-by: Nathan Lynch <redacted>
---
 arch/powerpc/platforms/pseries/mobility.c | 76 +++++++++++++++++++++--
 1 file changed, 71 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
index dc6abf164db7..1b8ae221b98a 100644
--- a/arch/powerpc/platforms/pseries/mobility.c
+++ b/arch/powerpc/platforms/pseries/mobility.c

@@ -345,6 +345,73 @@ void post_mobility_fixup(void)

...

quoted

+
+static int wait_for_vasi_session_suspending(u64 handle)
+{
+	unsigned long state;
+	bool keep_polling;
+	int ret;
+
+	/*
+	 * Wait for transition from H_VASI_ENABLED to
+	 * H_VASI_SUSPENDING. Treat anything else as an error.
+	 */
+	do {
+		keep_polling = false;
+		ret = poll_vasi_state(handle, &state);
+		if (ret != 0)
+			break;
+
+		switch (state) {
+		case H_VASI_SUSPENDING:
+			break;
+		case H_VASI_ENABLED:
+			keep_polling = true;
+			ssleep(1);
+			break;
+		default:
+			pr_err("unexpected H_VASI_STATE result %lu\n", state);
+			ret = -EIO;
+			break;
+		}
+	} while (keep_polling);

This seems like it could be simpler?

eg:

	while (true) {
		ret = poll_vasi_state(handle, &state);

		if (ret != 0 || state == H_VASI_SUSPENDING)
			break;
		else if (state == H_VASI_ENABLED)
			ssleep(1);
		else {
			pr_err("unexpected H_VASI_STATE result %lu\n", state);
			ret = -EIO;
			break;
		}
	}


Or did I miss something?

No I think you're right, thanks.