Messages in this thread Patch in this message | | | From | "Kirill A. Shutemov" <> | Subject | [PATCH, RFC] shmat: introduce flag SHM_MAP_HINT | Date | Mon, 6 Oct 2008 17:37:59 +0300 |
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It allows interpret attach address as a hint, not as exact address.
Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name> Cc: Andi Kleen <andi@firstfloor.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> --- include/linux/shm.h | 1 + ipc/shm.c | 4 ++-- 2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/include/linux/shm.h b/include/linux/shm.h index eca6235..2a637b8 100644 --- a/include/linux/shm.h +++ b/include/linux/shm.h @@ -55,6 +55,7 @@ struct shmid_ds { #define SHM_RND 020000 /* round attach address to SHMLBA boundary */ #define SHM_REMAP 040000 /* take-over region on attach */ #define SHM_EXEC 0100000 /* execution access */ +#define SHM_MAP_HINT 0200000 /* interpret attach address as a hint */ /* super user shmctl commands */ #define SHM_LOCK 11 diff --git a/ipc/shm.c b/ipc/shm.c index e77ec69..19462bb 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -819,7 +819,7 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr) if (shmid < 0) goto out; else if ((addr = (ulong)shmaddr)) { - if (addr & (SHMLBA-1)) { + if (!(shmflg & SHM_MAP_HINT) && (addr & (SHMLBA-1))) { if (shmflg & SHM_RND) addr &= ~(SHMLBA-1); /* round down */ else @@ -828,7 +828,7 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr) #endif goto out; } - flags = MAP_SHARED | MAP_FIXED; + flags = (shmflg & SHM_MAP_HINT ? 0 : MAP_FIXED) | MAP_SHARED; } else { if ((shmflg & SHM_REMAP)) goto out; -- 1.5.6.5.GIT
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