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pstore: Convert "psinfo" locking to mutex

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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>
This commit is contained in:
Kees Cook 2020-05-04 19:31:36 -07:00
parent c30b20cd96
commit cab12fd049
1 changed files with 4 additions and 4 deletions
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8
fs/pstore/platform.c
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@ -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)