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powerpc/kernel: Block interrupts when updating TIDR

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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: ec233ede4c ("powerpc: Add support for setting SPRN_TIDR")
Cc: stable@vger.kernel.org # v4.15+
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Sukadev Bhattiprolu
2017-11-28 13:39:43 -06:00
committed by Michael Ellerman
parent 902bdc5745
commit 384dfd627f
1 changed files with 9 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

15
arch/powerpc/kernel/process.c
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@@ -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 @@ again:
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 @@ again:
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);
} }
/* /*