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| author | David Woodhouse <dwmw2@infradead.org> | 2006-10-01 17:55:53 +0100 |
|---|---|---|
| committer | David Woodhouse <dwmw2@infradead.org> | 2006-10-01 17:55:53 +0100 |
| commit | 8a84fc15ae5cafcc366dd85cf8e1ab2040679abc (patch) | |
| tree | 5d8dce194c9667fa92e9ec9f545cec867a9a1e0d /include/linux/uaccess.h | |
| parent | 28b79ff9661b22e4c41c0d00d4ab8503e810f13d (diff) | |
| parent | 82965addad66fce61a92c5f03104ea90b0b87124 (diff) | |
| download | cachepc-linux-8a84fc15ae5cafcc366dd85cf8e1ab2040679abc.tar.gz cachepc-linux-8a84fc15ae5cafcc366dd85cf8e1ab2040679abc.zip | |
Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6
Manually resolve conflict in include/mtd/Kbuild
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Diffstat (limited to 'include/linux/uaccess.h')
| -rw-r--r-- | include/linux/uaccess.h | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h index 391e7ed1eb3f..a48d7f11c7be 100644 --- a/include/linux/uaccess.h +++ b/include/linux/uaccess.h @@ -19,4 +19,26 @@ static inline unsigned long __copy_from_user_nocache(void *to, #endif /* ARCH_HAS_NOCACHE_UACCESS */ +/** + * probe_kernel_address(): safely attempt to read from a location + * @addr: address to read from - its type is type typeof(retval)* + * @retval: read into this variable + * + * Safely read from address @addr into variable @revtal. If a kernel fault + * happens, handle that and return -EFAULT. + * We ensure that the __get_user() is executed in atomic context so that + * do_page_fault() doesn't attempt to take mmap_sem. This makes + * probe_kernel_address() suitable for use within regions where the caller + * already holds mmap_sem, or other locks which nest inside mmap_sem. + */ +#define probe_kernel_address(addr, retval) \ + ({ \ + long ret; \ + \ + inc_preempt_count(); \ + ret = __get_user(retval, addr); \ + dec_preempt_count(); \ + ret; \ + }) + #endif /* __LINUX_UACCESS_H__ */ |