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: powerpc: block interrupts when updating TIDR

PATCH Applied Sukadev Bhattiprolu 2 participants 2 messages Dec 1, 2017 – Jan 29, 2018 PowerPC

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PATCH 1/1 : powerpc: block interrupts when updating TIDR

From: Sukadev Bhattiprolu <[email protected]>
Date: Tue, 28 Nov 2017 13:39:43 -0600
Subject: [PATCH 1/1]: powerpc: 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.

Signed-off-by Sukadev Bhattiprolu <[email protected]>
---
 arch/powerpc/kernel/process.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)
arch/powerpc/kernel/process.c +9 -6
index bfdd783..aa8dbb9 100644
@@ -1509,14 +1509,15 @@ 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;

@@ -1524,9 +1525,9 @@ 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;
 	}
 

@@ -1535,9 +1536,11 @@ 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);
 }
 
 /*
Signature · 1 line
2.7.4
Applied
#1 lore raw
Quoted 10 lines · Sukadev Bhattiprolu

From: Sukadev Bhattiprolu <[email protected]>
Date: Tue, 28 Nov 2017 13:39:43 -0600
Subject: [PATCH 1/1]: powerpc: 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.

Signed-off-by Sukadev Bhattiprolu <[email protected]>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/384dfd627f1ee67d028e6f14c6e9bf

cheers