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 <nath...@linux.ibm.com>
---
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)
return;
}
+static int poll_vasi_state(u64 handle, unsigned long *res)
+{
+ unsigned long retbuf[PLPAR_HCALL_BUFSIZE];
+ long hvrc;
+ int ret;
+
+ hvrc = plpar_hcall(H_VASI_STATE, retbuf, handle);
+ switch (hvrc) {
+ case H_SUCCESS:
+ ret = 0;
+ *res = retbuf[0];
+ break;
+ case H_PARAMETER:
+ ret = -EINVAL;
+ break;
+ case H_FUNCTION:
+ ret = -EOPNOTSUPP;
+ break;
+ case H_HARDWARE:
+ default:
+ pr_err("unexpected H_VASI_STATE result %ld\n", hvrc);
+ ret = -EIO;
+ break;
+ }
+ return ret;
+}
+
+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);
+
+ /*
+ * Proceed even if H_VASI_STATE is unavailable. If H_JOIN or
+ * ibm,suspend-me are also unimplemented, we'll recover then.
+ */
+ if (ret == -EOPNOTSUPP)
+ ret = 0;
+
+ return ret;
+}
+
static ssize_t migration_store(struct class *class,
struct class_attribute *attr, const char *buf,
size_t count)
@@ -356,12 +423,11 @@ static ssize_t migration_store(struct class *class,
if (rc)
return rc;
- do {
- rc = rtas_ibm_suspend_me_unsafe(streamid);
- if (rc == -EAGAIN)
- ssleep(1);
- } while (rc == -EAGAIN);
+ rc = wait_for_vasi_session_suspending(streamid);
+ if (rc)
+ return rc;
+ rc = rtas_ibm_suspend_me_unsafe(streamid);
if (rc)
return rc;
--
2.25.4
