Commit b2a2a84d authored by Hervé Fache's avatar Hervé Fache Committed by David Woodhouse
Browse files

mtd: phram: dot not crash when built-in and passing boot param 



This patch is based on Ville Herva's similar patch to block2mtd.

Trying to pass a parameter through the kernel command line when built-in would
crash the kernel, as phram_setup() was called so early that kmalloc() was not
functional yet.

This patch only saves the parameter string at the early boot stage, and parses
it later when init_phram() is called. The same happens in both module and
built-in cases.

With this patch, I can boot with a statically-compiled phram, and mount a
ext2 root fs from physical RAM, without the need for a initrd.

This has been tested in built-in and module cases, with and without a
parameter string.

Artem: amended comments a bit

Signed-off-by: default avatarHervé Fache <h-fache@ti.com>
Signed-off-by: default avatarArtem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: default avatarDavid Woodhouse <David.Woodhouse@intel.com>
parent 09ef90d9

drivers/mtd/devices/phram.c

+30 −3
Original line number Diff line number Diff line
@@ -39,7 +39,8 @@ static int phram_erase(struct mtd_info *mtd, struct erase_info *instr) 


	memset(start + instr->addr, 0xff, instr->len);



	/* This'll catch a few races. Free the thing before returning :)

	/*

	 * This'll catch a few races. Free the thing before returning :)

	 * I don't feel at all ashamed. This kind of thing is possible anyway

	 * with flash, but unlikely.

	 */
@@ -204,7 +205,17 @@ static inline void kill_final_newline(char *str) 
	return 1;		\

} while (0)



static int phram_setup(const char *val, struct kernel_param *kp)

/*

 * This shall contain the module parameter if any. It is of the form:

 * - phram=<device>,<address>,<size> for module case

 * - phram.phram=<device>,<address>,<size> for built-in case

 * We leave 64 bytes for the device name, 12 for the address and 12 for the

 * size.

 * Example: phram.phram=rootfs,0xa0000000,512Mi

 */

static __initdata char phram_paramline[64+12+12];



static int phram_setup(const char *val)

{

	char buf[64+12+12], *str = buf;

	char *token[3];
@@ -253,12 +264,28 @@ static int phram_setup(const char *val, struct kernel_param *kp) 
	return ret;

}



module_param_call(phram, phram_setup, NULL, NULL, 000);

static int __init phram_param_call(const char *val, struct kernel_param *kp)

{

	/*

	 * This function is always called before 'init_phram()', whether

	 * built-in or module.

	 */

	if (strlen(val) >= sizeof(phram_paramline))

		return -ENOSPC;

	strcpy(phram_paramline, val);



	return 0;

}



module_param_call(phram, phram_param_call, NULL, NULL, 000);

MODULE_PARM_DESC(phram, "Memory region to map. \"phram=<name>,<start>,<length>\"");





static int __init init_phram(void)

{

	if (phram_paramline[0])

		return phram_setup(phram_paramline);



	return 0;

}

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