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author | David S. Miller <davem@davemloft.net> | 2013-07-03 14:50:41 -0700 |
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committer | David S. Miller <davem@davemloft.net> | 2013-07-03 14:55:13 -0700 |
commit | 0c1072ae0242fbdffd9a0bba36e7a7033d287f9c (patch) | |
tree | e0f4dbdbf5078d4a707911177e7bdc17a70bdce5 /kernel/context_tracking.c | |
parent | c50cd357887acf9fd7af3a5d492911bd825555a2 (diff) | |
parent | 8bb495e3f02401ee6f76d1b1d77f3ac9f079e376 (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.c | 41 |
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 |