From: Svenning Sørensen <[email protected]> Subject: IPC: bugfix for msgrcv with msgtyp < 0
According to 'man msgrcv': "If msgtyp is less than 0, the first message of the lowest type that is less than or equal to the absolute value of msgtyp shall be received." Bug: The kernel only returns a message if its type is 1; other messages with type < abs(msgtype) will never get returned. Fix: After having traversed the list to find the first message with the lowest type, we need to actually return that message. This regression was introduced by commit daaf74cf0867e3042090d56d10b194d6265b4684 Author: Peter Hurley <[email protected]> AuthorDate: Tue Apr 30 19:15:04 2013 -0700 Commit: Linus Torvalds <[email protected]> CommitDate: Wed May 1 08:12:57 2013 -0700 ipc: refactor msg list search into separate function Signed-off-by: Svenning Soerensen <[email protected]> Reviewed-by: Peter Hurley <[email protected]> Cc: <[email protected]> Signed-off-by: Andrew Morton <[email protected]> --- ipc/msg.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff -puN ipc/msg.c~ipc-bugfix-for-msgrcv-with-msgtyp-0 ipc/msg.c --- a/ipc/msg.c~ipc-bugfix-for-msgrcv-with-msgtyp-0 +++ a/ipc/msg.c @@ -839,7 +839,7 @@ static inline void free_copy(struct msg_ static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode) { - struct msg_msg *msg; + struct msg_msg *msg, *found = NULL; long count = 0; list_for_each_entry(msg, &msq->q_messages, m_list) { @@ -848,6 +848,7 @@ static struct msg_msg *find_msg(struct m *msgtyp, mode)) { if (mode == SEARCH_LESSEQUAL && msg->m_type != 1) { *msgtyp = msg->m_type - 1; + found = msg; } else if (mode == SEARCH_NUMBER) { if (*msgtyp == count) return msg; @@ -857,7 +858,7 @@ static struct msg_msg *find_msg(struct m } } - return ERR_PTR(-EAGAIN); + return found ?: ERR_PTR(-EAGAIN); } long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgflg, _ -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
