From b2a2a84d35e0f42ad26e326ec4258f6a8b8eecbe Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Herv=C3=A9=20Fache?= Date: Tue, 13 Mar 2012 16:07:53 +0100 Subject: [PATCH] mtd: phram: dot not crash when built-in and passing boot param MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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: Hervé Fache Signed-off-by: Artem Bityutskiy Signed-off-by: David Woodhouse --- drivers/mtd/devices/phram.c | 33 ++++++++++++++++++++++++++++++--- 1 file changed, 30 insertions(+), 3 deletions(-) diff --git a/drivers/mtd/devices/phram.c b/drivers/mtd/devices/phram.c index 9d2bf1741fb..3d91ace1ee4 100644 --- a/drivers/mtd/devices/phram.c +++ b/drivers/mtd/devices/phram.c @@ -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=,
, for module case + * - phram.phram=,
, 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=,,\""); static int __init init_phram(void) { + if (phram_paramline[0]) + return phram_setup(phram_paramline); + return 0; }