cvs commit: src/sys/sys firmware.h src/sys/kern subr_firmware.c

[John Baldwin]

On Monday 19 June 2006 14:24, Ian Dowse wrote:
> In message <200606190915.50962.jhb at freebsd.org>, John Baldwin writes:
> >On Friday 16 June 2006 20:47, Ian Dowse wrote:
> >>  - driver calls firmware_get, firmware image loaded and fp->file set to 
non-NULL
> >>  - manually kldload some_module_that_depends_on_firmware_image
> >>  - driver calls firmware_put, unloadentry called and sets fp->file = NULL
> >
> >In practice no modules depend on firmware modules. :)  I think we should
> >take the approach of not clearing fp->file in unloadentry() however.
> >That would result in correct behavior in every case I can think of (or as
> >close to correct as you can get).  In the above case the
> >linker_file_unload() would have fail leaving the firmware module around.
> 
> How about the following patch? In the above case linker_file_unload()
> would actually succeed because the linker file reference count is
> just dropping from 2 to 1, so we'd get a negative reference count
> later if we kept fp->file non-NULL after it returns.
> 
> Ian
> 
> Index: subr_firmware.c
> ===================================================================
> RCS file: /home/ncvs/src/sys/kern/subr_firmware.c,v
> retrieving revision 1.2
> diff -u -r1.2 subr_firmware.c
> --- subr_firmware.c	10 Jun 2006 17:04:07 -0000	1.2
> +++ subr_firmware.c	19 Jun 2006 18:15:21 -0000
> @@ -206,7 +206,7 @@
>  {
>  	struct firmware *fp;
>  	linker_file_t file;
> -	int i;
> +	int i, err;
>  
>  	mtx_lock(&firmware_mtx);
>  	for (;;) {
> @@ -226,9 +226,18 @@
>  		fp->file = NULL;
>  		mtx_unlock(&firmware_mtx);
>  
> -		linker_file_unload(file, LINKER_UNLOAD_NORMAL);
> -
> +		err = linker_file_unload(file, LINKER_UNLOAD_NORMAL);
>  		mtx_lock(&firmware_mtx);
> +		if (err) {
> +			/*
> +			 * If linker_file_unload() failed then we still hold
> +			 * a reference on the module so it should not be
> +			 * possible for it to go away or be re-registered.
> +			 */
> +			KASSERT(fp->file == NULL,
> +			    ("firmware entry reused while referenced!"));
> +			fp->file = file;
> +		}
>  	}
>  	mtx_unlock(&firmware_mtx);
>  }
> 

Ok.

-- 
John Baldwin