diff mbox

[dpdk-dev,v6,2/8] rte_rwlock.h: gcc8 sign conversion warnings

Message ID 152686806330.58694.1166818586734360461.stgit@localhost.localdomain (mailing list archive)
State Superseded, archived
Delegated to: Thomas Monjalon
Headers

Checks

Context Check Description
ci/checkpatch success coding style OK
ci/Intel-compilation success Compilation OK

Commit Message

Andy Green May 21, 2018, 2:01 a.m. UTC 
  In file included from /projects/lagopus/src/dpdk/
build/include/rte_rwlock.h:12,
                 from ./mgr/lock.h:24,
                 from ./mgr/sock_io.c:54:
/projects/lagopus/src/dpdk/build/include/generic/
rte_rwlock.h: In function 'rte_rwlock_read_lock':
/projects/lagopus/src/dpdk/build/include/generic/
rte_rwlock.h:74:12: warning: conversion to 'uint32_t'
{aka 'unsigned int'} from 'int32_t' {aka 'int'} may
change the sign of the result [-Wsign-conversion]
            x, x + 1);
            ^
/projects/lagopus/src/dpdk/build/include/generic/
rte_rwlock.h:74:17: warning: conversion to 'uint32_t'
{aka 'unsigned int'} from 'int' may change the sign
of the result [-Wsign-conversion]
            x, x + 1);
               ~~^~~
/projects/lagopus/src/dpdk/build/include/generic/
rte_rwlock.h: In function 'rte_rwlock_write_lock':
/projects/lagopus/src/dpdk/build/include/generic/
rte_rwlock.h:110:15: warning: unsigned conversion
from 'int' to 'uint32_t' {aka 'unsigned int'}
changes value from '-1' to '4294967295'
[-Wsign-conversion]
            0, -1);
               ^~

Again in this case we are making explicit the exact cast
that was always happening implicitly.  The patch does not
change the generated code.

The int32_t temp "x" is required to be signed to detect
a < 0 error condition from the lock status.  Afterwards,
it has always been implicitly cast to uint32_t when it
is used in the arguments to rte_atomic32_cmpset()...
gcc8.1 objects to the implicit cast now and requires us
to cast it explicitly.

Fixes: af75078fec ("first public release")
Signed-off-by: Andy Green <andy@warmcat.com>
---
 lib/librte_eal/common/include/generic/rte_rwlock.h |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Bruce Richardson May 21, 2018, 12:10 p.m. UTC | #1 
On Mon, May 21, 2018 at 10:01:03AM +0800, Andy Green wrote:
> In file included from /projects/lagopus/src/dpdk/
> build/include/rte_rwlock.h:12,
>                  from ./mgr/lock.h:24,
>                  from ./mgr/sock_io.c:54:
> /projects/lagopus/src/dpdk/build/include/generic/
> rte_rwlock.h: In function 'rte_rwlock_read_lock':
> /projects/lagopus/src/dpdk/build/include/generic/
> rte_rwlock.h:74:12: warning: conversion to 'uint32_t'
> {aka 'unsigned int'} from 'int32_t' {aka 'int'} may
> change the sign of the result [-Wsign-conversion]
>             x, x + 1);
>             ^
> /projects/lagopus/src/dpdk/build/include/generic/
> rte_rwlock.h:74:17: warning: conversion to 'uint32_t'
> {aka 'unsigned int'} from 'int' may change the sign
> of the result [-Wsign-conversion]
>             x, x + 1);
>                ~~^~~
> /projects/lagopus/src/dpdk/build/include/generic/
> rte_rwlock.h: In function 'rte_rwlock_write_lock':
> /projects/lagopus/src/dpdk/build/include/generic/
> rte_rwlock.h:110:15: warning: unsigned conversion
> from 'int' to 'uint32_t' {aka 'unsigned int'}
> changes value from '-1' to '4294967295'
> [-Wsign-conversion]
>             0, -1);
>                ^~
> 
> Again in this case we are making explicit the exact cast
> that was always happening implicitly.  The patch does not
> change the generated code.
> 
> The int32_t temp "x" is required to be signed to detect
> a < 0 error condition from the lock status.  Afterwards,
> it has always been implicitly cast to uint32_t when it
> is used in the arguments to rte_atomic32_cmpset()...
> gcc8.1 objects to the implicit cast now and requires us
> to cast it explicitly.
> 
> Fixes: af75078fec ("first public release")
> Signed-off-by: Andy Green <andy@warmcat.com>
> ---

Acked-by: Bruce Richardson <bruce.richardson@intel.com>
diff mbox

Patch

diff --git a/lib/librte_eal/common/include/generic/rte_rwlock.h b/lib/librte_eal/common/include/generic/rte_rwlock.h
index 899e9bc43..5751a0e6d 100644
--- a/lib/librte_eal/common/include/generic/rte_rwlock.h
+++ b/lib/librte_eal/common/include/generic/rte_rwlock.h
@@ -71,7 +71,7 @@  rte_rwlock_read_lock(rte_rwlock_t *rwl)
 			continue;
 		}
 		success = rte_atomic32_cmpset((volatile uint32_t *)&rwl->cnt,
-					      x, x + 1);
+					      (uint32_t)x, (uint32_t)(x + 1));
 	}
 }
 
@@ -107,7 +107,7 @@  rte_rwlock_write_lock(rte_rwlock_t *rwl)
 			continue;
 		}
 		success = rte_atomic32_cmpset((volatile uint32_t *)&rwl->cnt,
-					      0, -1);
+					      0, (uint32_t)-1);
 	}
 }