Messages in this thread Patch in this message | | | From | (Christoph Bartelmus) | Subject | PROBLEM: serial port driver grabs occupied port | Date | 02 Feb 2002 23:21:00 GMT |
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Hi,
there's a problem with linux/drivers/char/serial.c that appears when using the LIRC serial port drivers (see http://www.lirc.org). Here's how to reproduce the problem:
1. Load the lirc_serial module (included in the LIRC package). This module uses request_region() for the used serial port's IO space.
2. Load the kernel serial module. In rs_init() the available serial ports are initialized. For the port already claimed by the lirc_serial module check_region() fails and state->type for this port stays PORT_UNKNOWN.
Now the problem: 3. Open the /dev/ttySx for the port that is occupied by the lirc_serial module. rs_open() does not check the state of the serial port and returns no error. Now you can use setserial to hijack the port... lirc_serial stops working.
The patch below fixes the problem for me (tested with 2.2.19 and 2.2.20). There's one problem with this patch though. Once state->type ist PORT_UNKNOWN for a port there's no way to reclaim the port with e.g. setserial unless you remove the serial port module and load it again.
Christoph
PS: I'm not subscribed, cc me if replying.
--- Schnipp --- --- linux/drivers/char/serial.c Sun Mar 25 18:37:31 2001 +++ serial.c Tue Jan 15 18:20:59 2002 @@ -928,6 +928,11 @@ unsigned short ICP; #endif
+ if(state->type == PORT_UNKNOWN) + { + return -ENODEV; + } + page = get_free_page(GFP_KERNEL); if (!page) return -ENOMEM; @@ -1738,7 +1743,10 @@ info->xmit_fifo_size = state->xmit_fifo_size = new_serial.xmit_fifo_size;
- release_region(state->port,8); + if(old_state.type != PORT_UNKNOWN) + { + release_region(state->port,8); + } if (change_port || change_irq) { /* * We need to shutdown the serial port at the old @@ -1750,8 +1758,14 @@ info->hub6 = state->hub6 = new_serial.hub6; } if (state->type != PORT_UNKNOWN) + { + retval=check_region(state->port,8); + if(retval<0) + { + return retval; + } request_region(state->port,8,"serial(set)"); - + } check_and_exit: if (!state->port || !state->type) @@ -3586,3 +3600,4 @@ return kmem_start; } #endif + --- Schnipp --- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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