From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by nf-out-0910.google.com with SMTP id c10so1670677nfd.6 for ; Tue, 07 Oct 2008 09:14:10 -0700 (PDT) From: "Kirill A. Shutemov" Subject: [PATCH, v3] shmat: introduce flag SHM_MAP_NOT_FIXED Date: Tue, 7 Oct 2008 19:15:17 +0300 Message-Id: <1223396117-8118-1-git-send-email-kirill@shutemov.name> Sender: owner-linux-mm@kvack.org Return-Path: To: linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: "Kirill A. Shutemov" , Andi Kleen , Ingo Molnar , Arjan van de Ven , Hugh Dickins , KOSAKI Motohiro , Alan Cox , Ulrich Drepper , Andrew Morton List-ID: If SHM_MAP_NOT_FIXED specified and shmaddr is not NULL, then the kernel takes shmaddr as a hint about where to place the mapping. The address of the mapping is returned as the result of the call. It's similar to mmap() without MAP_FIXED. Signed-off-by: Kirill A. Shutemov Cc: Andi Kleen Cc: Ingo Molnar Cc: Arjan van de Ven Cc: Hugh Dickins Cc: KOSAKI Motohiro Cc: Alan Cox Cc: Ulrich Drepper Cc: Andrew Morton --- include/linux/shm.h | 2 ++ ipc/shm.c | 7 ++++--- 2 files changed, 6 insertions(+), 3 deletions(-) diff --git a/include/linux/shm.h b/include/linux/shm.h index eca6235..fd288eb 100644 --- a/include/linux/shm.h +++ b/include/linux/shm.h @@ -55,6 +55,8 @@ 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_NOT_FIXED 0200000 /* interpret attach address as a search + * hint */ /* super user shmctl commands */ #define SHM_LOCK 11 diff --git a/ipc/shm.c b/ipc/shm.c index e77ec69..54f3c61 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_NOT_FIXED) && (addr & (SHMLBA-1))) { if (shmflg & SHM_RND) addr &= ~(SHMLBA-1); /* round down */ else @@ -828,7 +828,8 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr) #endif goto out; } - flags = MAP_SHARED | MAP_FIXED; + flags = MAP_SHARED | + (shmflg & SHM_MAP_NOT_FIXED ? 0 : MAP_FIXED); } else { if ((shmflg & SHM_REMAP)) goto out; @@ -892,7 +893,7 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr) sfd->vm_ops = NULL; down_write(¤t->mm->mmap_sem); - if (addr && !(shmflg & SHM_REMAP)) { + if (addr && !(shmflg & (SHM_REMAP|SHM_MAP_NOT_FIXED))) { err = -EINVAL; if (find_vma_intersection(current->mm, addr, addr + size)) goto invalid; -- 1.5.6.5.GIT -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org