: TIOCX: Do not autoload TIOCX & FPGA drivers

[PATCH]: ia64/sn : Do not autoload TIOCX & FPGA driver

When built-in the TIOCX driver has functions exposed to the FPGA driver in the kernel. If a TIOCX is not found, this can lead to an oops when the FPGA attempts to register against the TIOCX driver.

This fix makes found_tiocx_device a static int which is queried when FPGA driver(s) attempt to register against the TIOCX driver. The functions cx_driver_register and cx_driver_unregister now return -ENODEV and NULL respectively if nr_tiocx_found = 0, preventing the FPGA driver from loading.

---
commit afcdf951ae21cea0298292aab6cb9186bf700e12 tree d30090ea4fd3c7696509afbc070370e89d47f1eb parent 88d7bd8cb9eb8d64bf7997600b0d64f7834047c5 author Prarit Bhargava <[email protected]> 1810817779 -0400 committer Prarit Bhargava <[email protected]> 1810817779 -0400

Index: arch/ia64/sn/kernel/tiocx.c
=================================--- eed337ef5e9ae7d62caa84b7974a11fddc7f06e0/arch/ia64/sn/kernel/tiocx.c (mode:100644 sha1:ab9b5f35c2a72ba9bf6a398029e888dbeed3d129) +++ d30090ea4fd3c7696509afbc070370e89d47f1eb/arch/ia64/sn/kernel/tiocx.c (mode:100644 sha1:043f05399bcb9d9456f0abd61288e3bbc8ecdbd4)
@@ -38,6 +38,7 @@
#define DBG(fmt...)
#endif

+static int nr_tiocx_found = 0; /* number of tiocx's found */
struct device_attribute dev_attr_cxdev_control;

/**
@@ -159,6 +160,9 @@
*/
int cx_driver_register(struct cx_drv *cx_driver) {
+ if (nr_tiocx_found = 0)
+ return -ENODEV;
+
cx_driver->driver.name = cx_driver->name; cx_driver->driver.bus = &tiocx_bus_type; cx_driver->driver.probe = cx_device_probe;
@@ -171,10 +175,12 @@
* cx_driver_unregister - Unregister the driver.
* @cx_driver: driver table (cx_drv struct) from driver */
-int cx_driver_unregister(struct cx_drv *cx_driver) +void cx_driver_unregister(struct cx_drv *cx_driver)
{
+ if (nr_tiocx_found = 0)
+ return;
+
driver_unregister(&cx_driver->driver);
- return 0;
}

/**
@@ -500,6 +506,9 @@
if (widgetp->xwi_hwid.part_num = TIO_CE_ASIC_PARTNUM)
continue;

+ /* found a TIOCX brick */
+ nr_tiocx_found++;
+
tio_corelet_reset(nasid, TIOCX_CORELET); tio_conveyor_enable(nasid);

@@ -515,6 +524,8 @@
/* It's ok if we find zero devices. */ DBG("found_tiocx_device= %d\n", found_tiocx_device);

+ if (nr_tiocx_found = 0)
+ return -ENODEV;
return 0;
}

Index: include/asm-ia64/sn/tiocx.h
=================================--- eed337ef5e9ae7d62caa84b7974a11fddc7f06e0/include/asm-ia64/sn/tiocx.h (mode:100644 sha1:c5447a504509ba07cbd1646acb37295a7e981801) +++ d30090ea4fd3c7696509afbc070370e89d47f1eb/include/asm-ia64/sn/tiocx.h (mode:100644 sha1:377c5b84f0bee045e79a91ae05046b95c82c6e96)
@@ -60,7 +60,7 @@
extern void tiocx_irq_free(struct sn_irq_info *);
extern int cx_device_unregister(struct cx_dev *);
extern int cx_device_register(nasid_t, int, int, struct hubdev_info *);
-extern int cx_driver_unregister(struct cx_drv *);
+extern void cx_driver_unregister(struct cx_drv *);
extern int cx_driver_register(struct cx_drv *);
extern uint64_t tiocx_dma_addr(uint64_t addr);
extern uint64_t tiocx_swin_base(int nasid);

On Fri, May 20, 2005 at 09:12:29AM -0400, Prarit Bhargava wrote:

| [PATCH]: ia64/sn : Do not autoload TIOCX & FPGA driver
| 
| When built-in the TIOCX driver has functions exposed to the FPGA driver
| in the kernel.  If a TIOCX is not found, this can lead to an oops when the
| FPGA attempts to register against the TIOCX driver.
| 
| This fix makes found_tiocx_device a static int which is queried when FPGA
| driver(s) attempt to register against the TIOCX driver.  The functions
| cx_driver_register and cx_driver_unregister now return -ENODEV and NULL
| respectively if nr_tiocx_found = 0, preventing the FPGA driver from loading.

Let's hold off on this until we understand the problem a little better. This seems to be dependent on config settings. For example, it works fine to have TIOCX and MBCS compiled statically if the kernel is compiled CONFIG_IA64_SGI_SN2.

Greg