[PATCH v5 1/6] kexec: move locking into do_kexec_load

[Arnd Bergmann]

From: Arnd Bergmann <a...@arndb.de>

The locking is the same between the native and compat version of
sys_kexec_load(), so it can be done in the common implementation
to reduce duplication.

Co-developed-by: Eric Biederman <ebied...@xmission.com>
Co-developed-by: Christoph Hellwig <h...@infradead.org>
Signed-off-by: Arnd Bergmann <a...@arndb.de>
---
 kernel/kexec.c | 44 ++++++++++++++++----------------------------
 1 file changed, 16 insertions(+), 28 deletions(-)

diff --git a/kernel/kexec.c b/kernel/kexec.c
index c82c6c06f051..9c7aef8f4bb6 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -110,6 +110,17 @@ static int do_kexec_load(unsigned long entry, unsigned 
long nr_segments,
        unsigned long i;
        int ret;
 
+       /*
+        * Because we write directly to the reserved memory region when loading
+        * crash kernels we need a mutex here to prevent multiple crash kernels
+        * from attempting to load simultaneously, and to prevent a crash kernel
+        * from loading over the top of a in use crash kernel.
+        *
+        * KISS: always take the mutex.
+        */
+       if (!mutex_trylock(&kexec_mutex))
+               return -EBUSY;
+
        if (flags & KEXEC_ON_CRASH) {
                dest_image = &kexec_crash_image;
                if (kexec_crash_image)
@@ -121,7 +132,8 @@ static int do_kexec_load(unsigned long entry, unsigned long 
nr_segments,
        if (nr_segments == 0) {
                /* Uninstall image */
                kimage_free(xchg(dest_image, NULL));
-               return 0;
+               ret = 0;
+               goto out_unlock;
        }
        if (flags & KEXEC_ON_CRASH) {
                /*
@@ -134,7 +146,7 @@ static int do_kexec_load(unsigned long entry, unsigned long 
nr_segments,
 
        ret = kimage_alloc_init(&image, entry, nr_segments, segments, flags);
        if (ret)
-               return ret;
+               goto out_unlock;
 
        if (flags & KEXEC_PRESERVE_CONTEXT)
                image->preserve_context = 1;
@@ -171,6 +183,8 @@ static int do_kexec_load(unsigned long entry, unsigned long 
nr_segments,
                arch_kexec_protect_crashkres();
 
        kimage_free(image);
+out_unlock:
+       mutex_unlock(&kexec_mutex);
        return ret;
 }
 
@@ -247,21 +261,8 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned 
long, nr_segments,
                ((flags & KEXEC_ARCH_MASK) != KEXEC_ARCH_DEFAULT))
                return -EINVAL;
 
-       /* Because we write directly to the reserved memory
-        * region when loading crash kernels we need a mutex here to
-        * prevent multiple crash  kernels from attempting to load
-        * simultaneously, and to prevent a crash kernel from loading
-        * over the top of a in use crash kernel.
-        *
-        * KISS: always take the mutex.
-        */
-       if (!mutex_trylock(&kexec_mutex))
-               return -EBUSY;
-
        result = do_kexec_load(entry, nr_segments, segments, flags);
 
-       mutex_unlock(&kexec_mutex);
-
        return result;
 }
 
@@ -301,21 +302,8 @@ COMPAT_SYSCALL_DEFINE4(kexec_load, compat_ulong_t, entry,
                        return -EFAULT;
        }
 
-       /* Because we write directly to the reserved memory
-        * region when loading crash kernels we need a mutex here to
-        * prevent multiple crash  kernels from attempting to load
-        * simultaneously, and to prevent a crash kernel from loading
-        * over the top of a in use crash kernel.
-        *
-        * KISS: always take the mutex.
-        */
-       if (!mutex_trylock(&kexec_mutex))
-               return -EBUSY;
-
        result = do_kexec_load(entry, nr_segments, ksegments, flags);
 
-       mutex_unlock(&kexec_mutex);
-
        return result;
 }
 #endif
-- 
2.29.2