NULL pointer dereference in uart_write_room().
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From: Alan Cox on 5 May 2008 06:50 > (5) uart_remove_one_port() is called by serial8250_register_port() > since ttyS0 is already in use but it is requested to be once removed. That means 8250_pnp is taking over and then trying to delete the console, so its breakage in the serial layer glue. Perhaps Russell has some ideas as its hard to tell what he intended to happen originally. Alan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Russell King on 6 May 2008 17:40 On Mon, May 05, 2008 at 11:30:55AM +0100, Alan Cox wrote: > > (5) uart_remove_one_port() is called by serial8250_register_port() > > since ttyS0 is already in use but it is requested to be once removed. > > That means 8250_pnp is taking over and then trying to delete the console, > so its breakage in the serial layer glue. Perhaps Russell has some ideas > as its hard to tell what he intended to happen originally. Is the rest of the report available somewhere? -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Ben Greear on 6 May 2008 12:30 Alan Cox wrote: >> (5) uart_remove_one_port() is called by serial8250_register_port() >> since ttyS0 is already in use but it is requested to be once removed. >> > > That means 8250_pnp is taking over and then trying to delete the console, > so its breakage in the serial layer glue. Perhaps Russell has some ideas > as its hard to tell what he intended to happen originally. > For what it's worth, I've been seeing this problem since about 2.6.23 on several different systems, and will be happy to test patches. The work-around of changing the .config file will be fine in the meantime, it seems. Thanks, Ben > Alan > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo(a)vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- Ben Greear <greearb(a)candelatech.com> Candela Technologies Inc http://www.candelatech.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Tetsuo Handa on 7 May 2008 11:30 Russell King wrote: > Is the rest of the report available somewhere? Yes. First report: http://lkml.org/lkml/2008/4/22/42 Second report: http://lkml.org/lkml/2008/5/2/22 Third report: http://lkml.org/lkml/2008/5/4/34 Regards. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Russell King on 7 May 2008 15:30
On Mon, May 05, 2008 at 11:30:55AM +0100, Alan Cox wrote: > > (5) uart_remove_one_port() is called by serial8250_register_port() > > since ttyS0 is already in use but it is requested to be once removed. > > That means 8250_pnp is taking over and then trying to delete the console, > so its breakage in the serial layer glue. Perhaps Russell has some ideas > as its hard to tell what he intended to happen originally. Looking at the original report, yes, it is (and will) try to delete the console. However, it's doing the best it can to tell the tty layer "oi, this is port going away, don't do anything more with it" by hanging it up. The real question is: why, after we try to hang up a specific port, is the tty layer continuing to use the port... and the answer is that the tty layer exempts the console from the usual hangup processing. IOW, you can not hang up the console port or indeed ever safely unregister it. Other solutions? Well, we could modify it in place but that gets awfully icky and racy with... the console, so we wouldn't actually be solving anything. The only other solution I can think of is to basically deny any change to the console port, so it never disappears, and therefore never becomes owned by PNP, PCI or whatever. Which also means that it'll probably mess up power management of it. I guess broken console PM is more preferable than oopsing peoples machines. -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |