pstore: Convert "psinfo" locking to mutex (cab12fd0) · Commits · 戴 / test

Currently pstore can only have a single backend attached at a time, and it tracks the active backend via "psinfo", under a lock. The locking for this does not need to be a spinlock, and in order to avoid may_sleep() issues during future changes to pstore_unregister(), switch to a mutex instead. Link: https://lore.kernel.org/lkml/20200506152114.50375-4-keescook@chromium.org/ Signed-off-by:

Kees Cook <keescook@chromium.org>

fs/pstore/platform.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -72,7 +72,7 @@ static DECLARE_WORK(pstore_work, pstore_dowork);
		* psinfo_lock just protects "psinfo" during
		* calls to pstore_register()
		*/
		static DEFINE_SPINLOCK(psinfo_lock);
		static DEFINE_MUTEX(psinfo_lock);
		struct pstore_info *psinfo;

		static char *backend;
		@@ -574,11 +574,11 @@ int pstore_register(struct pstore_info *psi)
		return -EINVAL;
		}

		spin_lock(&psinfo_lock);
		mutex_lock(&psinfo_lock);
		if (psinfo) {
		pr_warn("backend '%s' already loaded: ignoring '%s'\n",
		psinfo->name, psi->name);
		spin_unlock(&psinfo_lock);
		mutex_unlock(&psinfo_lock);
		return -EBUSY;
		}

		@@ -587,7 +587,7 @@ int pstore_register(struct pstore_info *psi)
		psinfo = psi;
		mutex_init(&psinfo->read_mutex);
		sema_init(&psinfo->buf_lock, 1);
		spin_unlock(&psinfo_lock);
		mutex_unlock(&psinfo_lock);


		if (psi->flags & PSTORE_FLAGS_DMESG)

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