[PATCH 5.15 124/245] powerpc/perf/hv-24x7: add missing RTAS retry status handling

Greg Kroah-Hartman
2024-02-27T14:07:53Z

From: Nathan Lynch <nathanl@linux.ibm.com>

[ Upstream commit cc4b26eab1859fa1a70711872caaf6414809973f ]

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
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/powerpc/perf/hv-24x7.c | 42 ++++++++++++++++---------------------
1 file changed, 18 insertions(+), 24 deletions(-)

diff --git a/arch/powerpc/perf/hv-24x7.c b/arch/powerpc/perf/hv-24x7.c
index 284ccc90fb11c..f68fa53f4b1a2 100644
--- 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. */
--
2.43.0