From ce0d3c0a6fb1422101498ef378c0851dabbbf67f Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 14 Jul 2015 22:03:57 +0200 Subject: genirq: Revert sparse irq locking around __cpu_up() and move it to x86 for now Boris reported that the sparse_irq protection around __cpu_up() in the generic code causes a regression on Xen. Xen allocates interrupts and some more in the xen_cpu_up() function, so it deadlocks on the sparse_irq_lock. There is no simple fix for this and we really should have the protection for all architectures, but for now the only solution is to move it to x86 where actual wreckage due to the lack of protection has been observed. Reported-and-tested-by: Boris Ostrovsky Fixes: a89941816726 'hotplug: Prevent alloc/free of irq descriptors during cpu up/down' Signed-off-by: Thomas Gleixner Cc: Peter Zijlstra Cc: xiao jin Cc: Joerg Roedel Cc: Borislav Petkov Cc: Yanmin Zhang Cc: xen-devel --- arch/x86/kernel/smpboot.c | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'arch/x86') diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index d3010aa79daf..b1f3ed9c7a9e 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -992,8 +992,17 @@ int native_cpu_up(unsigned int cpu, struct task_struct *tidle) common_cpu_up(cpu, tidle); + /* + * We have to walk the irq descriptors to setup the vector + * space for the cpu which comes online. Prevent irq + * alloc/free across the bringup. + */ + irq_lock_sparse(); + err = do_boot_cpu(apicid, cpu, tidle); + if (err) { + irq_unlock_sparse(); pr_err("do_boot_cpu failed(%d) to wakeup CPU#%u\n", err, cpu); return -EIO; } @@ -1011,6 +1020,8 @@ int native_cpu_up(unsigned int cpu, struct task_struct *tidle) touch_nmi_watchdog(); } + irq_unlock_sparse(); + return 0; } -- cgit v1.2.3