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[PATCH 3.2 105/107] parisc: Filter out spurious interrupts in PA-RISC irq handler

From Ben Hutchings <ben@decadent.org.uk>
Newsgroups linux.kernel
Subject [PATCH 3.2 105/107] parisc: Filter out spurious interrupts in PA-RISC irq handler
Date 2015-10-09 02:50 +0200
Message-ID <qhu2M-31O-55@gated-at.bofh.it> (permalink)
References <qhtzH-2tg-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

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3.2.72-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Helge Deller <deller@gmx.de>

commit b1b4e435e4ef7de77f07bf2a42c8380b960c2d44 upstream.

When detecting a serial port on newer PA-RISC machines (with iosapic) we have a
long way to go to find the right IRQ line, registering it, then registering the
serial port and the irq handler for the serial port. During this phase spurious
interrupts for the serial port may happen which then crashes the kernel because
the action handler might not have been set up yet.

So, basically it's a race condition between the serial port hardware and the
CPU which sets up the necessary fields in the irq sructs. The main reason for
this race is, that we unmask the serial port irqs too early without having set
up everything properly before (which isn't easily possible because we need the
IRQ number to register the serial ports).

This patch is a work-around for this problem. It adds checks to the CPU irq
handler to verify if the IRQ action field has been initialized already. If not,
we just skip this interrupt (which isn't critical for a serial port at bootup).
The real fix would probably involve rewriting all PA-RISC specific IRQ code
(for CPU, IOSAPIC, GSC and EISA) to use IRQ domains with proper parenting of
the irq chips and proper irq enabling along this line.

This bug has been in the PA-RISC port since the beginning, but the crashes
happened very rarely with currently used hardware.  But on the latest machine
which I bought (a C8000 workstation), which uses the fastest CPUs (4 x PA8900,
1GHz) and which has the largest possible L1 cache size (64MB each), the kernel
crashed at every boot because of this race. So, without this patch the machine
would currently be unuseable.

For the record, here is the flow logic:
1. serial_init_chip() in 8250_gsc.c calls iosapic_serial_irq().
2. iosapic_serial_irq() calls txn_alloc_irq() to find the irq.
3. iosapic_serial_irq() calls cpu_claim_irq() to register the CPU irq
4. cpu_claim_irq() unmasks the CPU irq (which it shouldn't!)
5. serial_init_chip() then registers the 8250 port.
Problems:
- In step 4 the CPU irq shouldn't have been registered yet, but after step 5
- If serial irq happens between 4 and 5 have finished, the kernel will crash

Cc: linux-parisc@vger.kernel.org
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---

 arch/parisc/kernel/irq.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/arch/parisc/kernel/irq.c
+++ b/arch/parisc/kernel/irq.c
@@ -336,8 +336,8 @@ void do_cpu_irq_mask(struct pt_regs *reg
 	struct pt_regs *old_regs;
 	unsigned long eirr_val;
 	int irq, cpu = smp_processor_id();
-#ifdef CONFIG_SMP
 	struct irq_desc *desc;
+#ifdef CONFIG_SMP
 	cpumask_t dest;
 #endif
 
@@ -350,8 +350,12 @@ void do_cpu_irq_mask(struct pt_regs *reg
 		goto set_out;
 	irq = eirr_to_irq(eirr_val);
 
-#ifdef CONFIG_SMP
+	/* Filter out spurious interrupts, mostly from serial port at bootup */
 	desc = irq_to_desc(irq);
+	if (unlikely(!desc->action))
+		goto set_out;
+
+#ifdef CONFIG_SMP
 	cpumask_copy(&dest, desc->irq_data.affinity);
 	if (irqd_is_per_cpu(&desc->irq_data) &&
 	    !cpu_isset(smp_processor_id(), dest)) {

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[PATCH 3.2 000/107] 3.2.72-rc1 review Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:30 +0200
  [PATCH 3.2 072/107] USB: option: add ZTE PIDs Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:30 +0200
  [PATCH 3.2 069/107] hfs,hfsplus: cache pages correctly between  bnode_create and bnode_free Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:30 +0200
  [PATCH 3.2 015/107] ocfs2: fix BUG in ocfs2_downconvert_thread_do_work() Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:30 +0200
  [PATCH 3.2 049/107] DRM - radeon: Don't link train DisplayPort on  HPD until we get the dpcd Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:30 +0200
  [PATCH 3.2 098/107] ipv6: lock socket in ip6_datagram_connect() Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:30 +0200
  [PATCH 3.2 024/107] libfc: Fix fc_fcp_cleanup_each_cmd() Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:30 +0200
  [PATCH 3.2 094/107] Initialize msg/shm IPC objects before doing  ipc_addid() Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:40 +0200
  [PATCH 3.2 060/107] drm/i915: Always mark the object as dirty  when used by the GPU Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:40 +0200
  [PATCH 3.2 047/107] eCryptfs: Invalidate dcache entries when  lower i_nlink is zero Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:40 +0200
  [PATCH 3.2 009/107] target: REPORT LUNS should return LUN 0 even  for dynamic ACLs Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:40 +0200
  [PATCH 3.2 095/107] net/tipc: initialize security state for new  connection  socket Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:40 +0200
  [PATCH 3.2 018/107] x86/ldt: Make modify_ldt synchronous Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:40 +0200
  [PATCH 3.2 036/107] PCI: Add VPD function 0 quirk for Intel  Ethernet devices Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:40 +0200
  [PATCH 3.2 016/107] net: Clone skb before setting peeked flag Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:40 +0200
  [PATCH 3.2 026/107] x86/ldt: Further fix FPU emulation Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:40 +0200
  [PATCH 3.2 029/107] sparc64: Fix userspace FPU register corruptions. Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:40 +0200
  [PATCH 3.2 023/107] libiscsi: Fix host busy blocking during  connection teardown Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:40 +0200
  [PATCH 3.2 019/107] x86/ldt: Correct LDT access in single  stepping logic Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:40 +0200
  [PATCH 3.2 017/107] net: Fix skb_set_peeked use-after-free bug Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:40 +0200
  [PATCH 3.2 005/107] crypto: ixp4xx - Remove bogus BUG_ON on  scattered dst buffer Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:40 +0200
  [PATCH 3.2 033/107] PCI: Fix TI816X class code quirk Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:40 +0200
  [PATCH 3.2 051/107] rtlwifi: rtl8192cu: Add new device ID Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:40 +0200
  [PATCH 3.2 032/107] [media] rc-core: fix remove uevent generation Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:40 +0200
  [PATCH 3.2 068/107] powerpc/MSI: Fix race condition in tearing  down MSI interrupts Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:40 +0200
  [PATCH 3.2 037/107] usb: gadget: m66592-udc: forever loop in  set_feature() Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:40 +0200
  [PATCH 3.2 054/107] xfs: return errors from partial I/O failures  to files Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:40 +0200
  [PATCH 3.2 103/107] ipv6: prevent fib6_run_gc() contention Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:40 +0200
  [PATCH 3.2 044/107] serial: 8250: bind to ALi Fast Infrared  Controller (ALI5123) Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:40 +0200
  [PATCH 3.2 070/107] hfs: fix B-tree corruption after insertion at  position 0 Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:40 +0200
  [PATCH 3.2 050/107] rtlwifi: rtl8192cu: Add new device ID Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:40 +0200
  [PATCH 3.2 048/107] xfs: Fix xfs_attr_leafblock definition Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:40 +0200
  [PATCH 3.2 025/107] ipc,sem: fix use after free on IPC_RMID after  a task using same semaphore set exits Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:40 +0200
  [PATCH 3.2 007/107] target/iscsi: Fix double free of a TUR  followed by a solicited NOPOUT Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:40 +0200
  [PATCH 3.2 081/107] usb: Use the USB_SS_MULT() macro to get the  burst multiplier. Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 079/107] s390/compat: correct uc_sigmask of the compat  signal frame Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 091/107] virtio-net: drop NETIF_F_FRAGLIST Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 053/107] drivercore: Fix unregistration path of  platform devices Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 006/107] USB: sierra: add 1199:68AB device ID Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 059/107] spi: spi-pxa2xx: Check status register to  determine if SSSR_TINT is disabled Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 002/107] pktgen: Require CONFIG_INET due to use of  IPv4 checksum function Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 085/107] cifs: use server timestamp for ntlmv2  authentication Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 066/107] ARM: 8429/1: disable GCC SRA optimization Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 061/107] Add radeon suspend/resume quirk for HP Compaq  dc5750. Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 046/107] USB: ftdi_sio: Added custom PID for  CustomWare products Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 013/107] perf: Fix fasync handling on inherited events Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 074/107] btrfs: skip waiting on ordered range for  special files Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 052/107] of/address: Don't loop forever in  of_find_matching_node_by_address(). Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 042/107] NFSv4: don't set SETATTR for O_RDONLY|O_EXCL Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 093/107] ipc/sem.c: fully initialize sem_array before  making it visible Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 039/107] auxdisplay: ks0108: fix refcount Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 083/107] usb: xhci: Clear XHCI_STATE_DYING on start Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 062/107] IB/uverbs: reject invalid or unknown opcodes Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 058/107] IB/uverbs: Fix race between ib_uverbs_open  and remove_one Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 102/107] perf tools: Fix build with perl 5.18 Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 075/107] ARM: 7880/1: Clear the IT state independent  of the Thumb-2 mode Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 105/107] parisc: Filter out spurious interrupts in  PA-RISC irq handler Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 100/107] net/ipv6: Correct PIM6 mrt_lock handling Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 030/107] dcache: Handle escaped paths in prepend_path Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 041/107] windfarm: decrement client count when  unregistering Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 076/107] ARM: fix Thumb2 signal handling when ARMv6 is  enabled Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 057/107] IB/mlx4: Use correct SL on AH query under RoCE Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 090/107] ipv6: addrconf: validate new MTU before  applying it Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 010/107] MIPS: Fix sched_getaffinity with MT FPAFF enabled Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 02:50 +0200
  [PATCH 3.2 063/107] Input: evdev - do not report errors form flush() Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 03:00 +0200
  [PATCH 3.2 078/107] ASoC: fix broken pxa SoC support Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 03:00 +0200
  [PATCH 3.2 064/107] crypto: ghash-clmulni: specify context size  for ghash async algorithm Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 03:00 +0200
  [PATCH 3.2 065/107] fs: create and use seq_show_option for escaping Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 03:00 +0200
  [PATCH 3.2 084/107] xhci: change xhci 1.0 only restrictions to  support xhci 1.1 Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 03:00 +0200
  [PATCH 3.2 071/107] perf header: Fixup reading of HEADER_NRCPUS  feature Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 03:00 +0200
  [PATCH 3.2 104/107] ipv6: update ip6_rt_last_gc every time GC is run Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 03:00 +0200
  [PATCH 3.2 055/107] IB/qib: Change lkey table allocation to  support more MRs Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 03:00 +0200
  [PATCH 3.2 073/107] Btrfs: fix read corruption of compressed and  shared extents Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 03:00 +0200
  Re: [PATCH 3.2 000/107] 3.2.72-rc1 review Guenter Roeck <linux@roeck-us.net> - 2015-10-09 03:00 +0200
    Re: [PATCH 3.2 000/107] 3.2.72-rc1 review Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 03:20 +0200
  [PATCH 3.2 077/107] x86/platform: Fix Geode LX timekeeping in the  generic x86 build Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 03:00 +0200
  [PATCH 3.2 087/107] ocfs2/dlm: fix deadlock when dispatch assert  master Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 03:00 +0200
  [PATCH 3.2 056/107] SUNRPC: xs_reset_transport must mark the  connection as disconnected Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 03:00 +0200
  [PATCH 3.2 082/107] xhci: give command abortion one more chance  before killing xhci Ben Hutchings <ben@decadent.org.uk> - 2015-10-09 03:00 +0200

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