| Re: [PATCH v6 02/10] ipc: "use key as id" functionality for resource get system ca [message #48367 is a reply to message #48352] |
Mon, 15 October 2012 19:39   |
ebiederm
Messages: 1354
Registered: February 2006
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Senior Member |
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Stanislav Kinsbursky <skinsbursky@parallels.com> writes:
> This patch introduces new IPC resource get request flag IPC_PRESET, which
> should be interpreted as a request to try to allocate IPC slot with number,
> starting from value resented by key. IOW, kernel will try
> allocate new segment in specified slot.
>
> Note: if desired slot is not emply, then next free slot will be used.
This way of handling things is pretty nasty.
- You don't fail if the requested id is not available.
- You don't allow assigning the key (which leads to the need to change
the key in later patches). Changing the creator uid and creator
gid and key is semantically ugly.
It would be much cleaner if you could instead add IPC_PRESET and then
extend the definition of the creation functions all by one argument.
aka
int msgget(key_t key, int msgflg, int id);
int semget(key_t key, int nsems, int semflg, int id);
int shmget(key_t key, size_t size, int shmflg, int id);
Where the extra id argument is ignored unless IPC_PRESET is specified.
Also msgget, semget, and shmget should fail if unregconized flags are
passed in. That ipcget doesn't do that today is bizarre.
Eric
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