[PATCH] powerpc/fadump: Add timeout to RTAS busy-wait loops

Adriano Vero
2026-04-06T06:40:30Z

The ibm,configure-kernel-dump RTAS call sites in
rtas_fadump_register(), rtas_fadump_unregister(), and
rtas_fadump_invalidate() polled indefinitely while firmware returned
a busy status. A misbehaving or hung firmware could stall these paths
forever, blocking fadump registration at boot or preventing clean
teardown.

Track the accumulated delay in a total_wait counter and bail out with
-ETIMEDOUT if it reaches RTAS_FADUMP_MAX_WAIT_MS (60 seconds) before
firmware signals completion. This follows the bounded busy-wait pattern
used in rtas-rtc.c.

Signed-off-by: Adriano Vero <litaliano00.contact@gmail.com>
---
arch/powerpc/platforms/pseries/rtas-fadump.c | 37 ++++++++++++++------
arch/powerpc/platforms/pseries/rtas-fadump.h | 6 ++++
2 files changed, 33 insertions(+), 10 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/rtas-fadump.c b/arch/powerpc/platforms/pseries/rtas-fadump.c
index eceb32893..b165f165c 100644
--- a/arch/powerpc/platforms/pseries/rtas-fadump.c
+++ b/arch/powerpc/platforms/pseries/rtas-fadump.c
@@ -181,7 +181,7 @@ static u64 rtas_fadump_get_bootmem_min(void)

static int rtas_fadump_register(struct fw_dump *fadump_conf)
{
- unsigned int wait_time, fdm_size;
+ unsigned int wait_time, total_wait, fdm_size;
int rc, err = -EIO;

/*
@@ -192,15 +192,20 @@ static int rtas_fadump_register(struct fw_dump *fadump_conf)
fdm_size = sizeof(struct rtas_fadump_section_header);
fdm_size += be16_to_cpu(fdm.header.dump_num_sections) * sizeof(struct rtas_fadump_section);

- /* TODO: Add upper time limit for the delay */
+ total_wait = 0;
do {
rc = rtas_call(fadump_conf->ibm_configure_kernel_dump, 3, 1,
NULL, FADUMP_REGISTER, &fdm, fdm_size);

wait_time = rtas_busy_delay_time(rc);
- if (wait_time)
+ if (wait_time) {
+ if (total_wait >= RTAS_FADUMP_MAX_WAIT_MS) {
+ pr_err("Timed out waiting for firmware to register fadump\n");
+ return -ETIMEDOUT;
+ }
+ total_wait += wait_time;
mdelay(wait_time);
-
+ }
} while (wait_time);

switch (rc) {
@@ -234,18 +239,24 @@ static int rtas_fadump_register(struct fw_dump *fadump_conf)

static int rtas_fadump_unregister(struct fw_dump *fadump_conf)
{
- unsigned int wait_time;
+ unsigned int wait_time, total_wait;
int rc;

- /* TODO: Add upper time limit for the delay */
+ total_wait = 0;
do {
rc = rtas_call(fadump_conf->ibm_configure_kernel_dump, 3, 1,
NULL, FADUMP_UNREGISTER, &fdm,
sizeof(struct rtas_fadump_mem_struct));

wait_time = rtas_busy_delay_time(rc);
- if (wait_time)
+ if (wait_time) {
+ if (total_wait >= RTAS_FADUMP_MAX_WAIT_MS) {
+ pr_err("Timed out waiting for firmware to unregister fadump\n");
+ return -ETIMEDOUT;
+ }
+ total_wait += wait_time;
mdelay(wait_time);
+ }
} while (wait_time);

if (rc) {
@@ -259,18 +270,24 @@ static int rtas_fadump_unregister(struct fw_dump *fadump_conf)

static int rtas_fadump_invalidate(struct fw_dump *fadump_conf)
{
- unsigned int wait_time;
+ unsigned int wait_time, total_wait;
int rc;

- /* TODO: Add upper time limit for the delay */
+ total_wait = 0;
do {
rc = rtas_call(fadump_conf->ibm_configure_kernel_dump, 3, 1,
NULL, FADUMP_INVALIDATE, fdm_active,
sizeof(struct rtas_fadump_mem_struct));

wait_time = rtas_busy_delay_time(rc);
- if (wait_time)
+ if (wait_time) {
+ if (total_wait >= RTAS_FADUMP_MAX_WAIT_MS) {
+ pr_err("Timed out waiting for firmware to invalidate fadump\n");
+ return -ETIMEDOUT;
+ }
+ total_wait += wait_time;
mdelay(wait_time);
+ }
} while (wait_time);

if (rc) {
diff --git a/arch/powerpc/platforms/pseries/rtas-fadump.h b/arch/powerpc/platforms/pseries/rtas-fadump.h
index c109abf6b..65fdab7b5 100644
--- a/arch/powerpc/platforms/pseries/rtas-fadump.h
+++ b/arch/powerpc/platforms/pseries/rtas-fadump.h
@@ -41,6 +41,12 @@
#define MAX_SECTIONS 10
#define RTAS_FADUMP_MAX_BOOT_MEM_REGS 7

+/*
+ * Maximum time to wait for firmware to respond to an
+ * ibm,configure-kernel-dump RTAS call before giving up.
+ */
+#define RTAS_FADUMP_MAX_WAIT_MS 60000U
+
/* Kernel Dump section info */
struct rtas_fadump_section {
__be32 request_flag;
--
2.53.0