diff options
| author | D Scott Phillips <scott@os.amperecomputing.com> | 2022-11-14 13:22:12 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-11-23 19:57:38 +0100 |
| commit | ab760791c0cfbb1d7a668f46a135264f56c8f018 (patch) | |
| tree | 9b511f0d18ede5c8fc0849694af1d1962ed31a87 /drivers/char | |
| parent | 7b51161696e803fd5f9ad55b20a64c2df313f95c (diff) | |
char: misc: Increase the maximum number of dynamic misc devices to 1048448
On AmpereOne, 128 dynamic misc devices is not enough for the per-cpu
coresight_tmc devices. Switch the dynamic minors allocator to an ida and
add logic to allocate in the ranges [0..127] and [256..1048575], leaving
[128..255] for static misc devices. Dynamic allocations start from 127
growing downwards and then increasing from 256, so device numbering for the
first 128 devices remain the same as before.
Signed-off-by: D Scott Phillips <scott@os.amperecomputing.com>
Link: https://lore.kernel.org/r/20221114212212.9279-1-scott@os.amperecomputing.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/char')
| -rw-r--r-- | drivers/char/misc.c | 41 |
1 files changed, 28 insertions, 13 deletions
diff --git a/drivers/char/misc.c b/drivers/char/misc.c index cba19bfdc44d..05727f0daa6b 100644 --- a/drivers/char/misc.c +++ b/drivers/char/misc.c @@ -61,7 +61,29 @@ static DEFINE_MUTEX(misc_mtx); * Assigned numbers, used for dynamic minors */ #define DYNAMIC_MINORS 128 /* like dynamic majors */ -static DECLARE_BITMAP(misc_minors, DYNAMIC_MINORS); +static DEFINE_IDA(misc_minors_ida); + +static int misc_minor_alloc(void) +{ + int ret; + + 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); + } + return ret; +} + +static void misc_minor_free(int minor) +{ + if (minor < DYNAMIC_MINORS) + ida_free(&misc_minors_ida, DYNAMIC_MINORS - minor - 1); + else if (minor > MISC_DYNAMIC_MINOR) + ida_free(&misc_minors_ida, minor); +} #ifdef CONFIG_PROC_FS static void *misc_seq_start(struct seq_file *seq, loff_t *pos) @@ -183,14 +205,13 @@ int misc_register(struct miscdevice *misc) mutex_lock(&misc_mtx); if (is_dynamic) { - int i = find_first_zero_bit(misc_minors, DYNAMIC_MINORS); + int i = misc_minor_alloc(); - if (i >= DYNAMIC_MINORS) { + if (i < 0) { err = -EBUSY; goto out; } - misc->minor = DYNAMIC_MINORS - i - 1; - set_bit(i, misc_minors); + misc->minor = i; } else { struct miscdevice *c; @@ -209,10 +230,7 @@ int misc_register(struct miscdevice *misc) misc, misc->groups, "%s", misc->name); if (IS_ERR(misc->this_device)) { if (is_dynamic) { - int i = DYNAMIC_MINORS - misc->minor - 1; - - if (i < DYNAMIC_MINORS && i >= 0) - clear_bit(i, misc_minors); + misc_minor_free(misc->minor); misc->minor = MISC_DYNAMIC_MINOR; } err = PTR_ERR(misc->this_device); @@ -240,16 +258,13 @@ EXPORT_SYMBOL(misc_register); void misc_deregister(struct miscdevice *misc) { - int i = DYNAMIC_MINORS - misc->minor - 1; - if (WARN_ON(list_empty(&misc->list))) return; mutex_lock(&misc_mtx); list_del(&misc->list); device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor)); - if (i < DYNAMIC_MINORS && i >= 0) - clear_bit(i, misc_minors); + misc_minor_free(misc->minor); mutex_unlock(&misc_mtx); } EXPORT_SYMBOL(misc_deregister); |