From: Sukadev Bhattiprolu Date: Tue, 28 Nov 2017 19:39:43 +0000 (-0600) Subject: powerpc/kernel: Block interrupts when updating TIDR X-Git-Tag: v4.16-rc1~93^2~13 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=384dfd627f1ee67d028e6f14c6e9bf5a1e2a7a24;p=linux.git powerpc/kernel: Block interrupts when updating TIDR clear_thread_tidr() is called in interrupt context as a part of delayed put of the task structure (i.e as a part of timer interrupt). To prevent a deadlock, block interrupts when holding vas_thread_id_lock to set/ clear TIDR for a task. Fixes: ec233ede4c86 ("powerpc: Add support for setting SPRN_TIDR") Cc: stable@vger.kernel.org # v4.15+ Signed-off-by: Sukadev Bhattiprolu Signed-off-by: Michael Ellerman --- diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index 2fd01c9045ba..69af583dce98 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -1515,14 +1515,15 @@ static int assign_thread_tidr(void) { int index; int err; + unsigned long flags; again: if (!ida_pre_get(&vas_thread_ida, GFP_KERNEL)) return -ENOMEM; - spin_lock(&vas_thread_id_lock); + spin_lock_irqsave(&vas_thread_id_lock, flags); err = ida_get_new_above(&vas_thread_ida, 1, &index); - spin_unlock(&vas_thread_id_lock); + spin_unlock_irqrestore(&vas_thread_id_lock, flags); if (err == -EAGAIN) goto again; @@ -1530,9 +1531,9 @@ static int assign_thread_tidr(void) return err; if (index > MAX_THREAD_CONTEXT) { - spin_lock(&vas_thread_id_lock); + spin_lock_irqsave(&vas_thread_id_lock, flags); ida_remove(&vas_thread_ida, index); - spin_unlock(&vas_thread_id_lock); + spin_unlock_irqrestore(&vas_thread_id_lock, flags); return -ENOMEM; } @@ -1541,9 +1542,11 @@ static int assign_thread_tidr(void) static void free_thread_tidr(int id) { - spin_lock(&vas_thread_id_lock); + unsigned long flags; + + spin_lock_irqsave(&vas_thread_id_lock, flags); ida_remove(&vas_thread_ida, id); - spin_unlock(&vas_thread_id_lock); + spin_unlock_irqrestore(&vas_thread_id_lock, flags); } /*