powerpc/perf/hv-24x7: add missing RTAS retry status handling

The ibm,get-system-parameter RTAS function may return -2 or 990x,
which indicate that the caller should try again. read_24x7_sys_info()
ignores this, allowing transient failures in reporting processor
module information.

Move the RTAS call into a coventional rtas_busy_delay()-based loop,
along with the parsing of results on success.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Fixes: 8ba214267382 ("powerpc/hv-24x7: Add rtas call in hv-24x7 driver to get processor details")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230125-b4-powerpc-rtas-queue-v3-2-26929c8cce78@linux.ibm.com

diff --git a/arch/powerpc/perf/hv-24x7.c b/arch/powerpc/perf/hv-24x7.c
index 8ce56837961e09374af7e4e1a23cca75d5beee43..5a8577447c9d176b84f139d272927b33883fa612 100644 (file)
--- a/arch/powerpc/perf/hv-24x7.c
+++ b/arch/powerpc/perf/hv-24x7.c
@@ -79,9 +79,8 @@ static u32 phys_coresperchip; /* Physical cores per chip */
  */
 void read_24x7_sys_info(void)
 {
-       int call_status, len, ntypes;
-
-       spin_lock(&rtas_data_buf_lock);
+       const s32 token = rtas_token("ibm,get-system-parameter");
+       int call_status;
 
        /*
         * Making system parameter: chips and sockets and cores per chip
@@ -91,32 +90,27 @@ void read_24x7_sys_info(void)
        phys_chipspersocket = 1;
        phys_coresperchip = 1;
 
-       call_status = rtas_call(rtas_token("ibm,get-system-parameter"), 3, 1,
-                               NULL,
-                               PROCESSOR_MODULE_INFO,
-                               __pa(rtas_data_buf),
-                               RTAS_DATA_BUF_SIZE);
+       do {
+               spin_lock(&rtas_data_buf_lock);
+               call_status = rtas_call(token, 3, 1, NULL, PROCESSOR_MODULE_INFO,
+                                       __pa(rtas_data_buf), RTAS_DATA_BUF_SIZE);
+               if (call_status == 0) {
+                       int ntypes = be16_to_cpup((__be16 *)&rtas_data_buf[2]);
+                       int len = be16_to_cpup((__be16 *)&rtas_data_buf[0]);
+
+                       if (len >= 8 && ntypes != 0) {
+                               phys_sockets = be16_to_cpup((__be16 *)&rtas_data_buf[4]);
+                               phys_chipspersocket = be16_to_cpup((__be16 *)&rtas_data_buf[6]);
+                               phys_coresperchip = be16_to_cpup((__be16 *)&rtas_data_buf[8]);
+                       }
+               }
+               spin_unlock(&rtas_data_buf_lock);
+       } while (rtas_busy_delay(call_status));
 
        if (call_status != 0) {
                pr_err("Error calling get-system-parameter %d\n",
                       call_status);
-       } else {
-               len = be16_to_cpup((__be16 *)&rtas_data_buf[0]);
-               if (len < 8)
-                       goto out;
-
-               ntypes = be16_to_cpup((__be16 *)&rtas_data_buf[2]);
-
-               if (!ntypes)
-                       goto out;
-
-               phys_sockets = be16_to_cpup((__be16 *)&rtas_data_buf[4]);
-               phys_chipspersocket = be16_to_cpup((__be16 *)&rtas_data_buf[6]);
-               phys_coresperchip = be16_to_cpup((__be16 *)&rtas_data_buf[8]);
        }
-
-out:
-       spin_unlock(&rtas_data_buf_lock);
 }
 
 /* Domains for which more than one result element are returned for each event. */