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misc: misc_minor_alloc to use ida for all dynamic/misc dynamic minors

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misc_minor_alloc was allocating id using ida for minor only in case of
MISC_DYNAMIC_MINOR but misc_minor_free was always freeing ids
using ida_free causing a mismatch and following warn:
> > WARNING: CPU: 0 PID: 159 at lib/idr.c:525 ida_free+0x3e0/0x41f
> > ida_free called for id=127 which is not allocated.
> > <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
...
> > [<60941eb4>] ida_free+0x3e0/0x41f
> > [<605ac993>] misc_minor_free+0x3e/0xbc
> > [<605acb82>] misc_deregister+0x171/0x1b3

misc_minor_alloc is changed to allocate id from ida for all minors
falling in the range of dynamic/ misc dynamic minors

Fixes: ab760791c0 ("char: misc: Increase the maximum number of dynamic misc devices to 1048448")
Signed-off-by: Vimal Agrawal <vimal.agrawal@sophos.com>
Reviewed-by: Dirk VanDerMerwe <dirk.vandermerwe@sophos.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20241021133812.23703-1-vimal.agrawal@sophos.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Vimal Agrawal 2024-10-21 13:38:12 +00:00 • committed by Greg Kroah-Hartman
parent 567a311d0a
commit 6d04d2b554
1 changed files with 29 additions and 8 deletions
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37
drivers/char/misc.c
View file

@ -63,16 +63,30 @@ static DEFINE_MUTEX(misc_mtx);
#define DYNAMIC_MINORS 128 /* like dynamic majors */
static DEFINE_IDA(misc_minors_ida);
static int misc_minor_alloc(void)
static int misc_minor_alloc(int minor)
{
int ret;
int ret = 0;
ret = ida_alloc_max(&misc_minors_ida, DYNAMIC_MINORS - 1, GFP_KERNEL);
if (ret >= 0) {
ret = DYNAMIC_MINORS - ret - 1;
if (minor == MISC_DYNAMIC_MINOR) {
/* allocate free id */
ret = ida_alloc_max(&misc_minors_ida, DYNAMIC_MINORS - 1, GFP_KERNEL);
if (ret >= 0) {
ret = DYNAMIC_MINORS - ret - 1;
} else {
ret = ida_alloc_range(&misc_minors_ida, MISC_DYNAMIC_MINOR + 1,
MINORMASK, GFP_KERNEL);
}
} else {
ret = ida_alloc_range(&misc_minors_ida, MISC_DYNAMIC_MINOR + 1,
MINORMASK, GFP_KERNEL);
/* specific minor, check if it is in dynamic or misc dynamic range */
if (minor < DYNAMIC_MINORS) {
minor = DYNAMIC_MINORS - minor - 1;
ret = ida_alloc_range(&misc_minors_ida, minor, minor, GFP_KERNEL);
} else if (minor > MISC_DYNAMIC_MINOR) {
ret = ida_alloc_range(&misc_minors_ida, minor, minor, GFP_KERNEL);
} else {
/* case of non-dynamic minors, no need to allocate id */
ret = 0;
}
}
return ret;
}
@ -219,7 +233,7 @@ int misc_register(struct miscdevice *misc)
mutex_lock(&misc_mtx);
if (is_dynamic) {
int i = misc_minor_alloc();
int i = misc_minor_alloc(misc->minor);
if (i < 0) {
err = -EBUSY;
@ -228,6 +242,7 @@ int misc_register(struct miscdevice *misc)
misc->minor = i;
} else {
struct miscdevice *c;
int i;
list_for_each_entry(c, &misc_list, list) {
if (c->minor == misc->minor) {
@ -235,6 +250,12 @@ int misc_register(struct miscdevice *misc)
goto out;
}
}
i = misc_minor_alloc(misc->minor);
if (i < 0) {
err = -EBUSY;
goto out;
}
}
dev = MKDEV(MISC_MAJOR, misc->minor);