[PATCH] pstore: replace spinlock_t by raw_spinlock_t

From: Wen Yang
Date: Mon Aug 19 2024 - 11:00:31 EST


pstore_dump() is called when both preemption and local IRQ are disabled,
and a spinlock is obtained, which is problematic for the RT kernel because
in this configuration, spinlocks are sleep locks.

Replace the spinlock_t with raw_spinlock_t to avoid sleeping in atomic context.

Signed-off-by: Wen Yang <wen.yang@xxxxxxxxx>
Cc: Kees Cook <kees@xxxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: "Guilherme G. Piccoli" <gpiccoli@xxxxxxxxxx>
Cc: linux-hardening@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
fs/pstore/platform.c | 8 ++++----
include/linux/pstore.h | 2 +-
2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 3497ede88aa0..84719e2bcbc4 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -288,13 +288,13 @@ static void pstore_dump(struct kmsg_dumper *dumper,
why = kmsg_dump_reason_str(reason);

if (pstore_cannot_block_path(reason)) {
- if (!spin_trylock_irqsave(&psinfo->buf_lock, flags)) {
+ if (!raw_spin_trylock_irqsave(&psinfo->buf_lock, flags)) {
pr_err("dump skipped in %s path because of concurrent dump\n",
in_nmi() ? "NMI" : why);
return;
}
} else {
- spin_lock_irqsave(&psinfo->buf_lock, flags);
+ raw_spin_lock_irqsave(&psinfo->buf_lock, flags);
}

kmsg_dump_rewind(&iter);
@@ -364,7 +364,7 @@ static void pstore_dump(struct kmsg_dumper *dumper,
total += record.size;
part++;
}
- spin_unlock_irqrestore(&psinfo->buf_lock, flags);
+ raw_spin_unlock_irqrestore(&psinfo->buf_lock, flags);

if (saved_ret) {
pr_err_once("backend (%s) writing error (%d)\n", psinfo->name,
@@ -503,7 +503,7 @@ int pstore_register(struct pstore_info *psi)
psi->write_user = pstore_write_user_compat;
psinfo = psi;
mutex_init(&psinfo->read_mutex);
- spin_lock_init(&psinfo->buf_lock);
+ raw_spin_lock_init(&psinfo->buf_lock);

if (psi->flags & PSTORE_FLAGS_DMESG)
allocate_buf_for_compression();
diff --git a/include/linux/pstore.h b/include/linux/pstore.h
index 638507a3c8ff..fed601053c51 100644
--- a/include/linux/pstore.h
+++ b/include/linux/pstore.h
@@ -182,7 +182,7 @@ struct pstore_info {
struct module *owner;
const char *name;

- spinlock_t buf_lock;
+ raw_spinlock_t buf_lock;
char *buf;
size_t bufsize;

--
2.25.1