From: Wei Yang <[email protected]>

Hi, Please folks help me review the patch below.

thanks

The patch fixes upon the issue described by the subject above.
The funciton shmget(shkey++, INT_SIZE,...) and shmat() only 
ensure that a page linear address range is avaiable. 
shmat() will return base_addr aligned on a page boundary, 
For x86 and ppc, since SHMLBA is equal to PAGE_SIZE, so the 
base_addr returned by shmat() is the same as the base_addr 
is aligned to next SHMLBA. But for mips architecture, 
SHMLBA is not equal to PAGE_SIZE(SHMLBA > PAGE_SIZE)
so when base_addr is aligned to next SHMLBA address. base_addr will 
expire a page range and the base_addr can already be used by the process,
then shmat(shkey, base_addr....) will return -1.
Therefore we should probe a bigger available virtual address space for 
ensuring that base_addr aligned to next SHMLBA always is available. that is
the base_addr aligned to next SHMLBA is not used by the process.


Signed-off-by: Wei Yang <[email protected]>
---
 testcases/kernel/syscalls/ipc/shmat/shmat01.c |   27 +++++++++++++++++++++++-
 1 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/testcases/kernel/syscalls/ipc/shmat/shmat01.c 
b/testcases/kernel/syscalls/ipc/shmat/shmat01.c
index 7c68459..344ad3f 100644
--- a/testcases/kernel/syscalls/ipc/shmat/shmat01.c
+++ b/testcases/kernel/syscalls/ipc/shmat/shmat01.c
@@ -65,6 +65,9 @@ void check_functionality(int);
 #define CASE1          20      /* memory location.                */
 
 int shm_id_1 = -1;
+#if defined(__mips__) || defined(__mips64)
+int shm_id_2 = -1;
+#endif
 
 void *base_addr;               /* By probing this address first, we can make
                                 * non-aligned addresses from it for different
@@ -262,14 +265,34 @@ void setup(void)
                tst_brkm(TBROK, cleanup, "Failed to create shared memory "
                         "resource 1 in setup()");
        }
-
        /* Probe an available linear address for attachment */
+#if defined(__mips__) || defined(__mips64)
+       /*
+        * For mips architecture, SHMLBA is not equal to PAGE_SIZE
+        * base_addr is not available address for process after 
+        * base_addr is aligned to next SHMLBA address
+        */
+       if ((shm_id_2 = shmget(shmkey++, SHMLBA, SHM_RW | IPC_CREAT | 
IPC_EXCL)) == -1) {
+               tst_brkm(TBROK, cleanup, "Failed to create shared memory ");
+       }
+       if ((base_addr = shmat(shm_id_2, NULL, 0)) == (void *) -1) {
+               rm_shm(shm_id_2);
+               tst_brkm(TBROK, cleanup, "Couldn't attach shared memory");
+       }
+       if (shmdt((const void *)base_addr) == -1) {
+               rm_shm(shm_id_2);
+               tst_brkm(TBROK, cleanup, "Couldn't detach shared memory");
+       }
+       rm_shm(shm_id_2);
+#else
        if ((base_addr = shmat(shm_id_1, NULL, 0)) == (void *)-1) {
                tst_brkm(TBROK, cleanup, "Couldn't attach shared memory");
        }
        if (shmdt((const void *)base_addr) == -1) {
                tst_brkm(TBROK, cleanup, "Couldn't detach shared memory");
        }
+#endif
+       
 
        /* some architectures (e.g. parisc) are strange, so better always align 
to
         * next SHMLBA address. */
@@ -299,4 +322,4 @@ void cleanup(void)
         */
        TEST_CLEANUP;
 
-}
\ No newline at end of file
+}
-- 
1.7.0.2


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