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

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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.

Introduce rtas_fadump_call(), a helper that wraps the common
busy-wait pattern shared by all three sites. The helper accumulates
the total delay and returns -ETIMEDOUT if firmware keeps returning a
busy status beyond RTAS_FADUMP_MAX_WAIT_MS (60 seconds). A pr_debug()
message is emitted on each busy iteration to aid diagnosis when the
timeout is hit.

Signed-off-by: Adriano Vero <adri.vero.dev@gmail.com>
Reviewed-by: Sourabh Jain <sourabhjain@linux.ibm.com>
[Maddy: Fixed newline after Signed-off-by]
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260506222024.30352-1-adri.vero.dev@gmail.com
This commit is contained in:
Adriano Vero 2026-05-07 00:20:23 +02:00 committed by Madhavan Srinivasan
parent b55b6b9ad7
commit b3580dd1c6
2 changed files with 53 additions and 33 deletions
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80
arch/powerpc/platforms/pseries/rtas-fadump.c
View File

@ -179,9 +179,42 @@ static u64 rtas_fadump_get_bootmem_min(void)
return RTAS_FADUMP_MIN_BOOT_MEM;
}
/*
* Helper to make an ibm,configure-kernel-dump RTAS call with a bounded
* busy-wait loop. Returns the RTAS return code on completion, or
* -ETIMEDOUT if firmware keeps returning a busy status beyond
* RTAS_FADUMP_MAX_WAIT_MS milliseconds.
*/
static int rtas_fadump_call(struct fw_dump *fadump_conf, int operation,
void *fdm_ptr, unsigned int fdm_size,
const char *op_name)
{
unsigned int wait_time, total_wait = 0;
int rc;
do {
rc = rtas_call(fadump_conf->ibm_configure_kernel_dump, 3, 1,
NULL, operation, fdm_ptr, fdm_size);
wait_time = rtas_busy_delay_time(rc);
if (wait_time) {
pr_debug("Firmware busy during fadump %s, waiting %ums (total %ums)\n",
op_name, wait_time, total_wait);
if (total_wait >= RTAS_FADUMP_MAX_WAIT_MS) {
pr_err("Timed out waiting for firmware to complete fadump %s\n",
op_name);
return -ETIMEDOUT;
}
total_wait += wait_time;
mdelay(wait_time);
}
} while (wait_time);
return rc;
}
static int rtas_fadump_register(struct fw_dump *fadump_conf)
{
unsigned int wait_time, fdm_size;
unsigned int fdm_size;
int rc, err = -EIO;
/*
@ -192,16 +225,10 @@ 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 */
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)
mdelay(wait_time);
} while (wait_time);
rc = rtas_fadump_call(fadump_conf, FADUMP_REGISTER, &fdm, fdm_size,
"register");
if (rc == -ETIMEDOUT)
return -ETIMEDOUT;
switch (rc) {
case 0:
@ -234,19 +261,12 @@ static int rtas_fadump_register(struct fw_dump *fadump_conf)
static int rtas_fadump_unregister(struct fw_dump *fadump_conf)
{
unsigned int wait_time;
int rc;
/* TODO: Add upper time limit for the delay */
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)
mdelay(wait_time);
} while (wait_time);
rc = rtas_fadump_call(fadump_conf, FADUMP_UNREGISTER, &fdm,
sizeof(struct rtas_fadump_mem_struct), "unregister");
if (rc == -ETIMEDOUT)
return -ETIMEDOUT;
if (rc) {
pr_err("Failed to un-register - unexpected error(%d).\n", rc);
@ -259,19 +279,13 @@ static int rtas_fadump_unregister(struct fw_dump *fadump_conf)
static int rtas_fadump_invalidate(struct fw_dump *fadump_conf)
{
unsigned int wait_time;
int rc;
/* TODO: Add upper time limit for the delay */
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)
mdelay(wait_time);
} while (wait_time);
rc = rtas_fadump_call(fadump_conf, FADUMP_INVALIDATE,
(void *)fdm_active,
sizeof(struct rtas_fadump_mem_struct), "invalidate");
if (rc == -ETIMEDOUT)
return -ETIMEDOUT;
if (rc) {
pr_err("Failed to invalidate - unexpected error (%d).\n", rc);

6
arch/powerpc/platforms/pseries/rtas-fadump.h
View File

@ -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;