Spin Lock question

NTDEV
1

Hi,

I have one question regarding using spin lock.

I have 2 structures:

typedef struct {

ULONG subcount1;

ULONG subcount2;

KSPIN_LOCK SubLock;

} SubStructure, *PSubStructure;

typedef struct {

SubStructure MySubStruct[NumberOfElements];

ULONG count1;

ULONG count2

KSPIN_LOCK Lock;

} MyStructure, *PMyStructure;

Should I use 2 spin locks (Lock and Sublock) to protect shared data from modifications ot it’s enough to use only one Lock? MyStructure contains SubStructure here.

Thank you,

Andrew

2

It depends, do you ever pass a PSubStructure pointer to an element of
MySubStruct? If the SubStructure can ever be accessed without the
MyStructure you need something. The reason I say something, is you should
look at Interlocked operations if the SubStructure elements are truly
ULONG’s they may eliminate the locks for you. Or you can look at a way to
reorganize the code to have only the Lock in MyStructure and use if for
everything.

–
Don Burn (MVP, Windows DDK)
Windows 2k/XP/2k3 Filesystem and Driver Consulting
Website: http://www.windrvr.com
Blog: http://msmvps.com/blogs/WinDrvr
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“Andrey Kamchatnikov” wrote in message
news:xxxxx@ntdev…
Hi,

I have one question regarding using spin lock.

I have 2 structures:

typedef struct {

ULONG subcount1;

ULONG subcount2;

KSPIN_LOCK SubLock;

} SubStructure, *PSubStructure;

typedef struct {

SubStructure MySubStruct[NumberOfElements];

ULONG count1;

ULONG count2

KSPIN_LOCK Lock;

} MyStructure, *PMyStructure;

Should I use 2 spin locks (Lock and Sublock) to protect shared data from
modifications ot it’s enough to use only one Lock? MyStructure contains
SubStructure here.

Thank you,

Andrew

3

this is an open ended question.

If you can guarentee that your inner struct will never be used independently
then u dnt need the two locks. But it it is, then you need it.

amitr0

On 7/10/07, Andrey Kamchatnikov wrote:
>
> Hi,
>
> I have one question regarding using spin lock.
>
> I have 2 structures:
>
>
> typedef struct {
>
> *ULONG subcount1; *
>
> *ULONG subcount2; *
>
> *KSPIN_LOCK SubLock; *
>
> *} SubStructure, PSubStructure;
>
>
>
> typedef struct {
>
> *SubStructure MySubStruct[NumberOfElements]; *
>
> *ULONG count1; *
>
> *ULONG count2 *
>
> KSPIN_LOCK Lock;
>
> *} MyStructure, PMyStructure;
>
>
>
> *Should I use 2 spin locks (Lock and Sublock) to protect shared data from
> modifications ot it’s enough to use only one Lock? MyStructure contains
> SubStructure here. *
>
>
>
> Thank you,
>
> **
>
> Andrew
>
> —
> Questions? First check the Kernel Driver FAQ at
> http://www.osronline.com/article.cfm?id=256
>
> To unsubscribe, visit the List Server section of OSR Online at
> http://www.osronline.com/page.cfm?name=ListServer
>

–

- amitr0

4

>Should I use 2 spin locks (Lock and Sublock) to protect shared data from

modifications ot it’s enough to use only one Lock? MyStructure contains
SubStructure here.

Both ways are OK, this is a design choice. If you have significant amount of
routines which only access Substructure but not Structure - create 2 locks,
otherwise, create 1.

–
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com