Date: Sun, 10 Aug 2003 12:15:53 -0400 From: Don Bowman <don@sandvine.com> To: "'freebsd-hackers@freebsd.org'" <freebsd-hackers@freebsd.org> Subject: hang in sio driver when interrupt occurs while in siocnputc() Message-ID: <FE045D4D9F7AED4CBFF1B3B813C8533702742201@mail.sandvine.com>
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I find that if the kernel is in the middle of a printf, is using a serial console, and a key is pressed, that i may end up stuck in the siointr. I added a counter to siointr1() so that if it receives more than 100 characters in a single interrupt it panics. What I find happens is that the chip (a winbond w83627HF in this case, 16550 compat) claims to have more characters to read (the fifo is not empty), but no interrupt is pending. The siointr1() loops forever on this, reading the com_data register. I created a simple kernel module that, on command from a sysctl, outputs many characters in a callout. When this is going, I hit enter a few times, and my panic occurs. Debugger(c03093aa) at Debugger+0x35 panic(c0330173,ce098000,3f8,ff807e60,8) at panic+0xb8 siointr1(ce098000,c0382788,3f8,ff807e44,c02c1e40) at siointr1+0x146 siointr(ce098000) at siointr+0x17 Xfastintr4(ff807e60,3f8,1c200,45,0) at Xfastintr4+0x20 siocnputc(c0362c44,45) at siocnputc+0x4d cnputc(45,1,63,0,ff807f40) at cnputc+0x4c putchar(45,ff807f60) at putchar+0x9d kvprintf(ce3bd75c,c01cb490,ff807f60,a,ff807f7c) at kvprintf+0x38e printf(ce3bd75c,45,0,ce3bd670,ff807fa8) at printf+0x44 so_timeout(0,40000000,ffffffff,0,ffffffff) at so_timeout+0x3b softclock(0,ff800018,c02e0010,ce090010,ffffffff) at softclock+0xfe doreti_swi(0,ff808000,0,0,f323a000) at doreti_swi+0xf idle_loop() at idle_loop+0x44 siocnputc() just takes spltty(), which doesn't prevent the interrupt from happening. this doesn't seem right, do you think that the siocn* routines should take COM_LOCK()? This is on RELENG_4. The system is SMP.
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