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Commit 384dfd62 authored by Sukadev Bhattiprolu's avatar Sukadev Bhattiprolu Committed by Michael Ellerman
Browse files

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: ec233ede ("powerpc: Add support for setting SPRN_TIDR")
Cc: stable@vger.kernel.org # v4.15+
Signed-off-by: default avatarSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 902bdc57

arch/powerpc/kernel/process.c

+9 −6
Original line number Original line Diff line number Diff line
@@ -1515,14 +1515,15 @@ static int assign_thread_tidr(void) 
{

{

	int index;

	int index;

	int err;

	int err;

	unsigned long flags;





again:

again:

	if (!ida_pre_get(&vas_thread_ida, GFP_KERNEL))

	if (!ida_pre_get(&vas_thread_ida, GFP_KERNEL))

		return -ENOMEM;

		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);

	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)

	if (err == -EAGAIN)

		goto again;

		goto again;
@@ -1530,9 +1531,9 @@ static int assign_thread_tidr(void) 
		return err;

		return err;





	if (index > MAX_THREAD_CONTEXT) {

	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);

		ida_remove(&vas_thread_ida, index);

		spin_unlock(&vas_thread_id_lock);

		spin_unlock_irqrestore(&vas_thread_id_lock, flags);

		return -ENOMEM;

		return -ENOMEM;

	}

	}
@@ -1541,9 +1542,11 @@ static int assign_thread_tidr(void) 




static void free_thread_tidr(int id)

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);

	ida_remove(&vas_thread_ida, id);

	spin_unlock(&vas_thread_id_lock);

	spin_unlock_irqrestore(&vas_thread_id_lock, flags);

}

}





/*

/*