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[MTD] [NOR] Fix deadlock in Intel chip driver caused by get_chip recursion

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This patch solves kernel deadlock issue seen on JFFF2 simultaneous 
operations. Detailed investigation of the issue showed that the kernel 
deadlock is caused by tons of recursive get_chip calls.

Signed-off-by: Alexey Korolev <akorolev@infradead.org>
Acked-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
This commit is contained in:
Alexey Korolev 2007-10-22 17:55:20 +01:00 committed by David Woodhouse
parent 2a754b51aa
commit 5a37cf19ef
1 changed files with 77 additions and 69 deletions
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146
drivers/mtd/chips/cfi_cmdset_0001.c
View file

@ -85,6 +85,7 @@ static int cfi_intelext_point (struct mtd_info *mtd, loff_t from, size_t len,
static void cfi_intelext_unpoint (struct mtd_info *mtd, u_char *addr, loff_t from,
size_t len);
static int chip_ready (struct map_info *map, struct flchip *chip, unsigned long adr, int mode);
static int get_chip(struct map_info *map, struct flchip *chip, unsigned long adr, int mode);
static void put_chip(struct map_info *map, struct flchip *chip, unsigned long adr);
#include "fwh_lock.h"
@ -641,73 +642,13 @@ static int cfi_intelext_partition_fixup(struct mtd_info *mtd,
/*
* *********** CHIP ACCESS FUNCTIONS ***********
*/
static int get_chip(struct map_info *map, struct flchip *chip, unsigned long adr, int mode)
static int chip_ready (struct map_info *map, struct flchip *chip, unsigned long adr, int mode)
{
DECLARE_WAITQUEUE(wait, current);
struct cfi_private *cfi = map->fldrv_priv;
map_word status, status_OK = CMD(0x80), status_PWS = CMD(0x01);
unsigned long timeo;
struct cfi_pri_intelext *cfip = cfi->cmdset_priv;
resettime:
timeo = jiffies + HZ;
retry:
if (chip->priv && (mode == FL_WRITING || mode == FL_ERASING || mode == FL_OTP_WRITE || mode == FL_SHUTDOWN)) {
/*
* OK. We have possibility for contension on the write/erase
* operations which are global to the real chip and not per
* partition. So let's fight it over in the partition which
* currently has authority on the operation.
*
* The rules are as follows:
*
* - any write operation must own shared->writing.
*
* - any erase operation must own _both_ shared->writing and
* shared->erasing.
*
* - contension arbitration is handled in the owner's context.
*
* The 'shared' struct can be read and/or written only when
* its lock is taken.
*/
struct flchip_shared *shared = chip->priv;
struct flchip *contender;
spin_lock(&shared->lock);
contender = shared->writing;
if (contender && contender != chip) {
/*
* The engine to perform desired operation on this
* partition is already in use by someone else.
* Let's fight over it in the context of the chip
* currently using it. If it is possible to suspend,
* that other partition will do just that, otherwise
* it'll happily send us to sleep. In any case, when
* get_chip returns success we're clear to go ahead.
*/
int ret = spin_trylock(contender->mutex);
spin_unlock(&shared->lock);
if (!ret)
goto retry;
spin_unlock(chip->mutex);
ret = get_chip(map, contender, contender->start, mode);
spin_lock(chip->mutex);
if (ret) {
spin_unlock(contender->mutex);
return ret;
}
timeo = jiffies + HZ;
spin_lock(&shared->lock);
spin_unlock(contender->mutex);
}
/* We now own it */
shared->writing = chip;
if (mode == FL_ERASING)
shared->erasing = chip;
spin_unlock(&shared->lock);
}
unsigned long timeo = jiffies + HZ;
switch (chip->state) {
@ -722,16 +663,11 @@ static int get_chip(struct map_info *map, struct flchip *chip, unsigned long adr
if (chip->priv && map_word_andequal(map, status, status_PWS, status_PWS))
break;
if (time_after(jiffies, timeo)) {
printk(KERN_ERR "%s: Waiting for chip to be ready timed out. Status %lx\n",
map->name, status.x[0]);
return -EIO;
}
spin_unlock(chip->mutex);
cfi_udelay(1);
spin_lock(chip->mutex);
/* Someone else might have been playing with it. */
goto retry;
return -EAGAIN;
}
case FL_READY:
@ -809,10 +745,82 @@ static int get_chip(struct map_info *map, struct flchip *chip, unsigned long adr
schedule();
remove_wait_queue(&chip->wq, &wait);
spin_lock(chip->mutex);
goto resettime;
return -EAGAIN;
}
}
static int get_chip(struct map_info *map, struct flchip *chip, unsigned long adr, int mode)
{
int ret;
retry:
if (chip->priv && (mode == FL_WRITING || mode == FL_ERASING
|| mode == FL_OTP_WRITE || mode == FL_SHUTDOWN)) {
/*
* OK. We have possibility for contention on the write/erase
* operations which are global to the real chip and not per
* partition. So let's fight it over in the partition which
* currently has authority on the operation.
*
* The rules are as follows:
*
* - any write operation must own shared->writing.
*
* - any erase operation must own _both_ shared->writing and
* shared->erasing.
*
* - contention arbitration is handled in the owner's context.
*
* The 'shared' struct can be read and/or written only when
* its lock is taken.
*/
struct flchip_shared *shared = chip->priv;
struct flchip *contender;
spin_lock(&shared->lock);
contender = shared->writing;
if (contender && contender != chip) {
/*
* The engine to perform desired operation on this
* partition is already in use by someone else.
* Let's fight over it in the context of the chip
* currently using it. If it is possible to suspend,
* that other partition will do just that, otherwise
* it'll happily send us to sleep. In any case, when
* get_chip returns success we're clear to go ahead.
*/
ret = spin_trylock(contender->mutex);
spin_unlock(&shared->lock);
if (!ret)
goto retry;
spin_unlock(chip->mutex);
ret = chip_ready(map, contender, contender->start, mode);
spin_lock(chip->mutex);
if (ret == -EAGAIN) {
spin_unlock(contender->mutex);
goto retry;
}
if (ret) {
spin_unlock(contender->mutex);
return ret;
}
spin_lock(&shared->lock);
spin_unlock(contender->mutex);
}
/* We now own it */
shared->writing = chip;
if (mode == FL_ERASING)
shared->erasing = chip;
spin_unlock(&shared->lock);
}
ret = chip_ready(map, chip, adr, mode);
if (ret == -EAGAIN)
goto retry;
return ret;
}
static void put_chip(struct map_info *map, struct flchip *chip, unsigned long adr)
{
struct cfi_private *cfi = map->fldrv_priv;