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Add extra guard space if needed 

Some buggy NPTL threading implementations include the guard area within
the stack size allocations.  In this case we need to allocate an extra
page to account for the guard area since we only have two pages of usable
stack on Linux.  Added an autoconf test that detects such implementations
by running a test program designed to segfault if the bug is present.
Set a flag NPTL_GUARD_WITHIN_STACK that is tested to decide if extra
stack space must be allocated for the guard area.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
This commit is contained in:
Ned Bass 2010-07-21 18:53:14 -07:00 committed by Brian Behlendorf
parent 75d868af70
commit be92edb218
2 changed files with 15 additions and 1 deletions
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6
lib/libzpool/include/sys/zfs_context.h
View File

@ -205,6 +205,12 @@ _NOTE(CONSTCOND) } while (0)
#define STACK_SIZE 24576 /* Solaris */
#endif
#ifdef NPTL_GUARD_WITHIN_STACK
#define EXTRA_GUARD_BYTES PAGESIZE
#else
#define EXTRA_GUARD_BYTES 0
#endif
/* in libzpool, p0 exists only to have its address taken */
typedef struct proc {
uintptr_t this_is_never_used_dont_dereference_it;

10
lib/libzpool/kernel.c
View File

@ -163,8 +163,16 @@ zk_thread_create(caddr_t stk, size_t stksize, thread_func_t func, void *arg,
* kernel space. PTHREAD_STACK_MIN is the minimum stack
* required for a NULL procedure in user space and is added
* in to the stack requirements.
*
* Some buggy NPTL threading implementations include the
* guard area within the stack size allocations. In
* this case we allocate an extra page to account for the
* guard area since we only have two pages of usable stack
* on Linux.
*/
stack = PTHREAD_STACK_MIN + MAX(stksize, STACK_SIZE);
stack = PTHREAD_STACK_MIN + MAX(stksize, STACK_SIZE) +
EXTRA_GUARD_BYTES;
VERIFY3S(pthread_attr_init(&attr), ==, 0);
VERIFY3S(pthread_attr_setstacksize(&attr, stack), ==, 0);