genirq: Set the irq thread policy without checking CAP_SYS_NICE

tpfaff6130 · KAGA-KOKO · commit bbfe65c219c6 · 2013-10-28T09:50:42.000+01:00
In commit ee23871 ("genirq: Set irq thread to RT priority on creation") we moved the assigment of the thread's priority from the thread's function into __setup_irq(). That function may run in user context for instance if the user opens an UART node and then driver calls requests in the ->open() callback. That user may not have CAP_SYS_NICE and so the irq thread won't run with the SCHED_OTHER policy. This patch uses sched_setscheduler_nocheck() so we omit the CAP_SYS_NICE check which is otherwise required for the SCHED_OTHER policy. [bigeasy: Rewrite the changelog] Signed-off-by: Thomas Pfaff <tpfaff@pcs.com> Cc: Ivo Sieben <meltedpianoman@gmail.com> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1381489240-29626-1-git-send-email-bigeasy@linutronix.de Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
@@ -956,7 +956,7 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
 			goto out_mput;
 		}
 
-		sched_setscheduler(t, SCHED_FIFO, &param);
+		sched_setscheduler_nocheck(t, SCHED_FIFO, &param);
 
 		/*
 		 * We keep the reference to the task struct even if

Original file line number	Diff line number	Diff line change
`@@ -956,7 +956,7 @@ __setup_irq(unsigned int irq, struct irq_desc desc, struct irqaction new)`
`956`	`956`	`goto out_mput;`
`957`	`957`	`}`
`958`	`958`
`959`		`- sched_setscheduler(t, SCHED_FIFO, &param);`
	`959`	`+ sched_setscheduler_nocheck(t, SCHED_FIFO, &param);`
`960`	`960`
`961`	`961`	`/*`
`962`	`962`	`* We keep the reference to the task struct even if`