[PATCH] powerpc/pseries/dlpar: handle ibm, configure-connector delay status

dlpar_configure_connector() has two problems in its handling of
ibm,configure-connector's return status:

1. When the status is -2 (busy, call again), we call
   ibm,configure-connector again immediately without checking whether
   to schedule, which can result in monopolizing the CPU.
2. Extended delay status (9900..9905) goes completely unhandled,
   causing the configuration to unnecessarily terminate.

Fix both of these issues by using rtas_busy_delay().

Fixes: ab519a011caa ("powerpc/pseries: Kernel DLPAR Infrastructure")
Signed-off-by: Nathan Lynch <redacted>
---
 arch/powerpc/platforms/pseries/dlpar.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/dlpar.c b/arch/powerpc/platforms/pseries/dlpar.c
index 16e86ba8aa20..f6b7749d6ada 100644
--- a/arch/powerpc/platforms/pseries/dlpar.c
+++ b/arch/powerpc/platforms/pseries/dlpar.c

@@ -127,7 +127,6 @@ void dlpar_free_cc_nodes(struct device_node *dn)
 #define NEXT_PROPERTY   3
 #define PREV_PARENT     4
 #define MORE_MEMORY     5
-#define CALL_AGAIN	-2
 #define ERR_CFG_USE     -9003
 
 struct device_node *dlpar_configure_connector(__be32 drc_index,

@@ -168,6 +167,9 @@ struct device_node *dlpar_configure_connector(__be32 drc_index,
 
 		spin_unlock(&rtas_data_buf_lock);
 
+		if (rtas_busy_delay(rc))
+			continue;
+
 		switch (rc) {
 		case COMPLETE:
 			break;

@@ -216,9 +218,6 @@ struct device_node *dlpar_configure_connector(__be32 drc_index,
 			last_dn = last_dn->parent;
 			break;
 
-		case CALL_AGAIN:
-			break;
-
 		case MORE_MEMORY:
 		case ERR_CFG_USE:
 		default:

-- 
2.29.2

Nathan Lynch [off-list ref] writes:

dlpar_configure_connector() has two problems in its handling of
ibm,configure-connector's return status:

1. When the status is -2 (busy, call again), we call
   ibm,configure-connector again immediately without checking whether
   to schedule, which can result in monopolizing the CPU.
2. Extended delay status (9900..9905) goes completely unhandled,
   causing the configuration to unnecessarily terminate.

Fix both of these issues by using rtas_busy_delay().

Fixes: ab519a011caa ("powerpc/pseries: Kernel DLPAR Infrastructure")
Signed-off-by: Nathan Lynch <redacted>

Just following up and adding some people to cc in hopes of getting some
review for this.

On 1/6/21 6:59 PM, Nathan Lynch wrote:

dlpar_configure_connector() has two problems in its handling of
ibm,configure-connector's return status:

1. When the status is -2 (busy, call again), we call
   ibm,configure-connector again immediately without checking whether
   to schedule, which can result in monopolizing the CPU.
2. Extended delay status (9900..9905) goes completely unhandled,
   causing the configuration to unnecessarily terminate.

Fix both of these issues by using rtas_busy_delay().

Fixes: ab519a011caa ("powerpc/pseries: Kernel DLPAR Infrastructure")
Signed-off-by: Nathan Lynch <redacted>

Reviewed-by: Tyrel Datwyler <tyreld@linux.ibm.com>

On Wed, 6 Jan 2021 20:59:00 -0600, Nathan Lynch wrote:

dlpar_configure_connector() has two problems in its handling of
ibm,configure-connector's return status:

1. When the status is -2 (busy, call again), we call
   ibm,configure-connector again immediately without checking whether
   to schedule, which can result in monopolizing the CPU.
2. Extended delay status (9900..9905) goes completely unhandled,
   causing the configuration to unnecessarily terminate.

[...]

Applied to powerpc/next.

[1/1] powerpc/pseries/dlpar: handle ibm, configure-connector delay status
      https://git.kernel.org/powerpc/c/768d70e19ba525debd571b36e6d0ab19956c63d7

cheers