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Groups > linux.kernel > #1618704 > unrolled thread
| Started by | Varsha Rao <rvarsha016@gmail.com> |
|---|---|
| First post | 2017-04-07 13:40 +0200 |
| Last post | 2017-04-09 07:30 +0200 |
| Articles | 3 — 2 participants |
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[PATCH 5/5] drivers: char: Replace bit operation functions with IDA allocator. Varsha Rao <rvarsha016@gmail.com> - 2017-04-07 13:40 +0200
Re: [PATCH 5/5] drivers: char: Replace bit operation functions with IDA allocator. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-07 17:50 +0200
Re: [PATCH 5/5] drivers: char: Replace bit operation functions with IDA allocator. Varsha Rao <rvarsha016@gmail.com> - 2017-04-09 07:30 +0200
| From | Varsha Rao <rvarsha016@gmail.com> |
|---|---|
| Date | 2017-04-07 13:40 +0200 |
| Subject | [PATCH 5/5] drivers: char: Replace bit operation functions with IDA allocator. |
| Message-ID | <ttApc-6sd-25@gated-at.bofh.it> |
Replace bit operation functions with IDA allocator functions. As IDA
allocation is simpler.
Signed-off-by: Varsha Rao <rvarsha016@gmail.com>
---
drivers/char/misc.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)
diff --git a/drivers/char/misc.c b/drivers/char/misc.c
index c9cd1ea..5786281 100644
--- a/drivers/char/misc.c
+++ b/drivers/char/misc.c
@@ -60,7 +60,7 @@ static DEFINE_MUTEX(misc_mtx);
* Assigned numbers, used for dynamic minors
*/
#define DYNAMIC_MINORS 64 /* like dynamic majors */
-static DECLARE_BITMAP(misc_minors, DYNAMIC_MINORS);
+static DEFINE_IDA(misc_minors_ida);
#ifdef CONFIG_PROC_FS
static void *misc_seq_start(struct seq_file *seq, loff_t *pos)
@@ -193,14 +193,18 @@ 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 = ida_simple_get(&misc_minors_ida, 0,
+ DYNAMIC_MINORS, GFP_KERNEL);
if (i >= DYNAMIC_MINORS) {
err = -EBUSY;
goto out;
- }
+ } else if (i < 0) {
+ err = i;
+ goto out;
+ } else {
misc->minor = DYNAMIC_MINORS - i - 1;
- set_bit(i, misc_minors);
+ }
} else {
struct miscdevice *c;
@@ -222,7 +226,7 @@ int misc_register(struct miscdevice *misc)
int i = DYNAMIC_MINORS - misc->minor - 1;
if (i < DYNAMIC_MINORS && i >= 0)
- clear_bit(i, misc_minors);
+ ida_simple_remove(&misc_minors_ida, i);
misc->minor = MISC_DYNAMIC_MINOR;
}
err = PTR_ERR(misc->this_device);
@@ -258,7 +262,7 @@ void misc_deregister(struct miscdevice *misc)
list_del(&misc->list);
device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
if (i < DYNAMIC_MINORS && i >= 0)
- clear_bit(i, misc_minors);
+ ida_simple_remove(&misc_minors_ida, i);
mutex_unlock(&misc_mtx);
}
--
2.9.3
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| From | Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
|---|---|
| Date | 2017-04-07 17:50 +0200 |
| Subject | Re: [PATCH 5/5] drivers: char: Replace bit operation functions with IDA allocator. |
| Message-ID | <ttEj7-G4-9@gated-at.bofh.it> |
| In reply to | #1618704 |
On Fri, Apr 07, 2017 at 05:04:41PM +0530, Varsha Rao wrote:
> Replace bit operation functions with IDA allocator functions. As IDA
> allocation is simpler.
But why does this matter?
>
> Signed-off-by: Varsha Rao <rvarsha016@gmail.com>
> ---
> drivers/char/misc.c | 16 ++++++++++------
> 1 file changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/char/misc.c b/drivers/char/misc.c
> index c9cd1ea..5786281 100644
> --- a/drivers/char/misc.c
> +++ b/drivers/char/misc.c
> @@ -60,7 +60,7 @@ static DEFINE_MUTEX(misc_mtx);
> * Assigned numbers, used for dynamic minors
> */
> #define DYNAMIC_MINORS 64 /* like dynamic majors */
> -static DECLARE_BITMAP(misc_minors, DYNAMIC_MINORS);
> +static DEFINE_IDA(misc_minors_ida);
>
> #ifdef CONFIG_PROC_FS
> static void *misc_seq_start(struct seq_file *seq, loff_t *pos)
> @@ -193,14 +193,18 @@ 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 = ida_simple_get(&misc_minors_ida, 0,
> + DYNAMIC_MINORS, GFP_KERNEL);
>
> if (i >= DYNAMIC_MINORS) {
> err = -EBUSY;
> goto out;
> - }
> + } else if (i < 0) {
> + err = i;
> + goto out;
> + } else {
> misc->minor = DYNAMIC_MINORS - i - 1;
> - set_bit(i, misc_minors);
> + }
Your indentation is now incorrect :(
> } else {
> struct miscdevice *c;
>
> @@ -222,7 +226,7 @@ int misc_register(struct miscdevice *misc)
> int i = DYNAMIC_MINORS - misc->minor - 1;
>
> if (i < DYNAMIC_MINORS && i >= 0)
> - clear_bit(i, misc_minors);
> + ida_simple_remove(&misc_minors_ida, i);
> misc->minor = MISC_DYNAMIC_MINOR;
> }
> err = PTR_ERR(misc->this_device);
> @@ -258,7 +262,7 @@ void misc_deregister(struct miscdevice *misc)
> list_del(&misc->list);
> device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
> if (i < DYNAMIC_MINORS && i >= 0)
> - clear_bit(i, misc_minors);
> + ida_simple_remove(&misc_minors_ida, i);
As much as I like the ida interface, I don't see why it is required to
use it here, you have not provided any justification for this patch at
all :(
thanks,
greg k-h
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| From | Varsha Rao <rvarsha016@gmail.com> |
|---|---|
| Date | 2017-04-09 07:30 +0200 |
| Subject | Re: [PATCH 5/5] drivers: char: Replace bit operation functions with IDA allocator. |
| Message-ID | <tudAe-76X-1@gated-at.bofh.it> |
| In reply to | #1618917 |
>> Replace bit operation functions with IDA allocator functions. As IDA
>> allocation is simpler.
>
> But why does this matter?
Few of the files in this driver is already using ida allocation. For maintaining
the uniformity I have used ida allocation.
Files using idr-ida interface
hw_random/virtio-rng.c
tpm/tpm-chip.c
ppdev.c
tpm/tpm-interface.c
tpm/tpm.h
>> if (is_dynamic) {
>> - int i = find_first_zero_bit(misc_minors, DYNAMIC_MINORS);
>> + int i = ida_simple_get(&misc_minors_ida, 0,
>> + DYNAMIC_MINORS, GFP_KERNEL);
>>
>> if (i >= DYNAMIC_MINORS) {
>> err = -EBUSY;
>> goto out;
>> - }
>> + } else if (i < 0) {
>> + err = i;
>> + goto out;
>> + } else {
>> misc->minor = DYNAMIC_MINORS - i - 1;
>> - set_bit(i, misc_minors);
>> + }
>
> Your indentation is now incorrect :(
I don't know but in the patch it has correct indentation as below.
- set_bit(i, misc_minors);
+ }
} else {
struct miscdevice *c;
>> } else {
>> struct miscdevice *c;
>>
>> @@ -222,7 +226,7 @@ int misc_register(struct miscdevice *misc)
>> int i = DYNAMIC_MINORS - misc->minor - 1;
>>
>> if (i < DYNAMIC_MINORS && i >= 0)
>> - clear_bit(i, misc_minors);
>> + ida_simple_remove(&misc_minors_ida, i);
>> misc->minor = MISC_DYNAMIC_MINOR;
>> }
>> err = PTR_ERR(misc->this_device);
>> @@ -258,7 +262,7 @@ void misc_deregister(struct miscdevice *misc)
>> list_del(&misc->list);
>> device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
>> if (i < DYNAMIC_MINORS && i >= 0)
>> - clear_bit(i, misc_minors);
>> + ida_simple_remove(&misc_minors_ida, i);
>
> As much as I like the ida interface, I don't see why it is required to
> use it here, you have not provided any justification for this patch at
> all :(
Here by the usage of ida interface, allocation will be simpler, faster and
more space efficient. Also conversion to it is simple. As I mentioned
earlier in this mail also to maintain uniformity of the driver.
Thanks,
Varsha Rao
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