[tip:irq/urgent] genirq: Set the irq thread policy without checking CAP_SYS_NICE

From: tip-bot for Thomas Pfaff
Date: Mon Oct 28 2013 - 04:56:23 EST

Commit-ID: bbfe65c219c638e19f1da5adab1005b2d68ca810
Gitweb: http://git.kernel.org/tip/bbfe65c219c638e19f1da5adab1005b2d68ca810
Author: Thomas Pfaff <tpfaff@xxxxxxx>
AuthorDate: Fri, 11 Oct 2013 13:00:40 +0200
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Mon, 28 Oct 2013 09:50:42 +0100

genirq: Set the irq thread policy without checking CAP_SYS_NICE

In commit ee23871389 ("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

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@xxxxxxx>
Cc: Ivo Sieben <meltedpianoman@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/1381489240-29626-1-git-send-email-bigeasy@xxxxxxxxxxxxx
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
kernel/irq/manage.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 514bcfd..3e59f95 100644
--- 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
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/