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authorDavid S. Miller <davem@davemloft.net>2013-07-03 14:50:41 -0700
committerDavid S. Miller <davem@davemloft.net>2013-07-03 14:55:13 -0700
commit0c1072ae0242fbdffd9a0bba36e7a7033d287f9c (patch)
treee0f4dbdbf5078d4a707911177e7bdc17a70bdce5 /kernel/context_tracking.c
parentc50cd357887acf9fd7af3a5d492911bd825555a2 (diff)
parent8bb495e3f02401ee6f76d1b1d77f3ac9f079e376 (diff)
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Conflicts: drivers/net/ethernet/freescale/fec_main.c drivers/net/ethernet/renesas/sh_eth.c net/ipv4/gre.c The GRE conflict is between a bug fix (kfree_skb --> kfree_skb_list) and the splitting of the gre.c code into seperate files. The FEC conflict was two sets of changes adding ethtool support code in an "!CONFIG_M5272" CPP protected block. Finally the sh_eth.c conflict was between one commit add bits set in the .eesr_err_check mask whilst another commit removed the .tx_error_check member and assignments. Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/context_tracking.c')
-rw-r--r--kernel/context_tracking.c41
1 files changed, 40 insertions, 1 deletions
diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index 65349f07b878..383f8231e436 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -15,7 +15,6 @@
*/
#include <linux/context_tracking.h>
-#include <linux/kvm_host.h>
#include <linux/rcupdate.h>
#include <linux/sched.h>
#include <linux/hardirq.h>
@@ -71,6 +70,46 @@ void user_enter(void)
local_irq_restore(flags);
}
+#ifdef CONFIG_PREEMPT
+/**
+ * preempt_schedule_context - preempt_schedule called by tracing
+ *
+ * The tracing infrastructure uses preempt_enable_notrace to prevent
+ * recursion and tracing preempt enabling caused by the tracing
+ * infrastructure itself. But as tracing can happen in areas coming
+ * from userspace or just about to enter userspace, a preempt enable
+ * can occur before user_exit() is called. This will cause the scheduler
+ * to be called when the system is still in usermode.
+ *
+ * To prevent this, the preempt_enable_notrace will use this function
+ * instead of preempt_schedule() to exit user context if needed before
+ * calling the scheduler.
+ */
+void __sched notrace preempt_schedule_context(void)
+{
+ struct thread_info *ti = current_thread_info();
+ enum ctx_state prev_ctx;
+
+ if (likely(ti->preempt_count || irqs_disabled()))
+ return;
+
+ /*
+ * Need to disable preemption in case user_exit() is traced
+ * and the tracer calls preempt_enable_notrace() causing
+ * an infinite recursion.
+ */
+ preempt_disable_notrace();
+ prev_ctx = exception_enter();
+ preempt_enable_no_resched_notrace();
+
+ preempt_schedule();
+
+ preempt_disable_notrace();
+ exception_exit(prev_ctx);
+ preempt_enable_notrace();
+}
+EXPORT_SYMBOL_GPL(preempt_schedule_context);
+#endif /* CONFIG_PREEMPT */
/**
* user_exit - Inform the context tracking that the CPU is