Commit 1bf8012f authored by Wen Yang's avatar Wen Yang Committed by Kees Cook
Browse files

pstore: replace spinlock_t by raw_spinlock_t 



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: default avatarWen Yang <wen.yang@linux.dev>
Cc: Kees Cook <kees@kernel.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Guilherme G. Piccoli <gpiccoli@igalia.com>
Cc: linux-hardening@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Link: https://lore.kernel.org/r/20240819145945.61274-1-wen.yang@linux.dev


Signed-off-by: default avatarKees Cook <kees@kernel.org>
parent a7050ca7

fs/pstore/platform.c

+4 −4
Original line number Diff line number Diff line
@@ -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();

include/linux/pstore.h

+1 −1
Original line number Diff line number Diff line
@@ -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;