Hi,
in my 2.4.24.3-rt3 kernel when the mii_queue() function shown below is called
the *second* time it crashes it calls spin_lock_irqsave(). The first time the
mii_queue() gets called it runs through spin_lock_irqsave() and at the end
through spin_unlock_irqrestore() without any error.
&fep->lock pointer is the same in all calls. And it only happens when
"Complete Preemption (Real-Time)" is active. It works fine when
"Preemptible Kernel (Low-Latency Desktop)" is active. Architecture is ARM
(in my case an i.MX27 CPU).
Any idea?
FEC ENET Version 0.2
Unable to handle kernel NULL pointer dereference at virtual address 00000000
pgd = c0004000
[00000000] *pgd=00000000
Internal error: Oops: 805 [#1] PREEMPT
Modules linked in:
CPU: 0 Not tainted (2.6.24.3-rt3 #22)
PC is at rt_spin_lock_slowlock+0x98/0x1f4
LR is at rt_spin_lock_slowlock+0x5c/0x1f4
pc : [<c01e5ee4>] lr : [<c01e5ea8>] psr: 60000093
sp : c7dd9e58 ip : c7de9cc2 fp : c7dd9eac
r10: 00000032 r9 : c7dea800 r8 : c7dead64
r7 : c7dead64 r6 : c7deac20 r5 : a0000013 r4 : c7dd8000
r3 : c7de9cc0 r2 : c7de9cc0 r1 : c7dead74 r0 : 00000000
Flags: nZCv IRQs off FIQs on Mode SVC_32 ISA ARM Segment kernel
Control: 0005317f Table: a0004000 DAC: 00000017
Process IRQ-50 (pid: 176, stack limit = 0xc7dd8268)
Stack: (0xc7dd9e58 to 0xc7dda000)
9e40: c7dd9e7c c7dd9e68
9e60: c0082e94 c005e908 00000000 c7dd9ea4 0011b3f5 c78017a8 c7dd9e94 c7dd9e88
9e80: 00000000 c7de9cf8 00000000 600e0000 c7deac20 c014b528 c7dead64 00000032
9ea0: c7dd9ebc c7dd9eb0 c01e6340 c01e5e5c c7dd9ecc c7dd9ec0 c01e6354 c01e62e4
9ec0: c7dd9ef4 c7dd9ed0 c014a920 c01e6354 00000000 c7deac20 00000001 d402b000
9ee0: c7dead64 c028bfd0 c7dd9f0c c7dd9ef8 c014b664 c014a904 c028bedc 600a0022
9f00: c7dd9f54 c7dd9f10 c014ab7c c014b5f0 c7dd9f2c d402b000 00800000 c005f16c
9f20: c7dd9f54 c7dd9f30 c004cb80 c7d3d960 00000000 c7dd8000 00000032 00000000
9f40: 00000000 00000032 c7dd9f84 c7dd9f58 c005ae70 c014a9f8 00000000 fffffffc
9f60: c7dd8000 c0268668 00000032 c7d3d960 00000000 c02686b4 c7dd9fac c7dd9f88
9f80: c005b5ac c005ae2c c7dd9fac fffffffc c0268668 c7dd8000 00000032 60000013
9fa0: c7dd9fdc c7dd9fb0 c005bfb8 c005b514 00000000 00000032 fffffffc c005bcc4
9fc0: 00000000 00000000 00000000 00000000 c7dd9ff4 c7dd9fe0 c0046dec c005bcd4
9fe0: 00000000 00000000 00000000 c7dd9ff8 c0033fa8 c0046dac 00000000 00000000
Backtrace:
[<c01e5e4c>] (rt_spin_lock_slowlock+0x0/0x1f4) from [<c01e6340>] (__rt_spin_lock+0x6c/0x70)
[<c01e62d4>] (__rt_spin_lock+0x0/0x70) from [<c01e6354>] (rt_spin_lock+0x10/0x14)
[<c01e6344>] (rt_spin_lock+0x0/0x14) from [<c014a920>] (mii_queue+0x2c/0xac)
[<c014a8f4>] (mii_queue+0x0/0xac) from [<c014b664>] (mii_discover_phy+0x84/0x9c)
r8:c028bfd0 r7:c7dead64 r6:d402b000 r5:00000001 r4:c7deac20
[<c014b5e0>] (mii_discover_phy+0x0/0x9c) from [<c014ab7c>] (fec_enet_interrupt+0x194/0x550)
r5:600a0022 r4:c028bedc
[<c014a9e8>] (fec_enet_interrupt+0x0/0x550) from [<c005ae70>] (handle_IRQ_event+0x54/0xec)
[<c005ae1c>] (handle_IRQ_event+0x0/0xec) from [<c005b5ac>] (thread_simple_irq+0xa8/0x110)
[<c005b504>] (thread_simple_irq+0x0/0x110) from [<c005bfb8>] (do_irqd+0x2f4/0x390)
r8:60000013 r7:00000032 r6:c7dd8000 r5:c0268668 r4:fffffffc
[<c005bcc4>] (do_irqd+0x0/0x390) from [<c0046dec>] (kthread+0x50/0x7c)
[<c0046d9c>] (kthread+0x0/0x7c) from [<c0033fa8>] (do_exit+0x0/0x7a8)
r5:00000000 r4:00000000
Code: e5973010 e594200c e3c33003 e1530002 (05800000)
---[ end trace 3c5ae69ea88154b1 ]---
note: IRQ-50[176] exited with preempt_count 1
[...]
static int mii_queue(struct net_device *dev, int regval, void (*func)(uint, struct net_device *))
{
struct fec_enet_private *fep;
unsigned long flags;
mii_list_t *mip;
int retval;
/* Add PHY address to register command.
*/
fep = netdev_priv(dev);
regval |= fep->phy_addr << 23;
retval = 0;
spin_lock_irqsave(&fep->lock,flags);
if ((mip = mii_free) != NULL) {
mii_free = mip->mii_next;
mip->mii_regval = regval;
mip->mii_func = func;
mip->mii_next = NULL;
if (mii_head) {
mii_tail->mii_next = mip;
mii_tail = mip;
}
else {
mii_head = mii_tail = mip;
fep->hwp->fec_mii_data = regval;
}
}
else {
retval = 1;
}
spin_unlock_irqrestore(&fep->lock,flags);
return(retval);
}
[...]
--
Dipl.-Ing. Juergen Beisert | http://www.pengutronix.de
Pengutronix - Linux Solutions for Science and Industry
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Vertretung Sued/Muenchen, Germany
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