From 2fb2d2a73f27bdd90a86d14c143e000e95d3c9d2 Mon Sep 17 00:00:00 2001 From: Alex Elder Date: Mon, 1 Dec 2014 07:53:08 -0600 Subject: [PATCH] greybus: define -EILSEQ to mean implementation error Reserve operation result code -EILSEQ to represent that the code that implements an operation is broken. This is used (initially) for any attempt to set the result to -EBADR (which is reserved for an operation in initial state), or for an attempt to set the result of an operation that is *not* in initial state to -EINPROGRESS. Note that we still use -EIO gb_operation_status_map() to represent a gb_operation_result value that isn't recognized. In gb_operation_result(), warn if operation->errno is -EBADR. That is another value that indicates the operation is not in a state where it's valid to query an operation's result. Update a bunch of comments above gb_operation_result_set() to explain constraints on operation->errno. Signed-off-by: Alex Elder Signed-off-by: Greg Kroah-Hartman --- drivers/staging/greybus/operation.c | 59 +++++++++++++++++++++-------- 1 file changed, 43 insertions(+), 16 deletions(-) diff --git a/drivers/staging/greybus/operation.c b/drivers/staging/greybus/operation.c index 8a023cbbf511..905c6de9e20e 100644 --- a/drivers/staging/greybus/operation.c +++ b/drivers/staging/greybus/operation.c @@ -70,44 +70,70 @@ struct gb_operation_msg_hdr { static DEFINE_SPINLOCK(gb_operations_lock); /* - * Set an operation's result. Initially an outgoing operation's - * errno value is -EBADR. If no error occurs before sending the - * request message the only valid value operation->errno can be - * set to is -EINPROGRESS, indicating the request has been (or - * rather is about to be) sent. At that point nobody should - * be looking at the result until the reponse arrives. + * Set an operation's result. + * + * Initially an outgoing operation's errno value is -EBADR. + * If no error occurs before sending the request message the only + * valid value operation->errno can be set to is -EINPROGRESS, + * indicating the request has been (or rather is about to be) sent. + * At that point nobody should be looking at the result until the + * reponse arrives. * * The first time the result gets set after the request has been * sent, that result "sticks." That is, if two concurrent threads * race to set the result, the first one wins. The return value * tells the caller whether its result was recorded; if not the - * has nothing more to do. + * caller has nothing more to do. + * + * The result value -EILSEQ is reserved to signal an implementation + * error; if it's ever observed, the code performing the request has + * done something fundamentally wrong. It is an error to try to set + * the result to -EBADR, and attempts to do so result in a warning, + * and -EILSEQ is used instead. Similarly, the only valid result + * value to set for an operation in initial state is -EINPROGRESS. + * Attempts to do otherwise will also record a (successful) -EILSEQ + * operation result. */ static bool gb_operation_result_set(struct gb_operation *operation, int result) { int prev; - /* Nobody should be setting -EBADR */ - if (WARN_ON(result == -EBADR)) - return false; - - /* Are we sending the request message? */ if (result == -EINPROGRESS) { - /* Yes, but verify the result has not already been set */ + /* + * -EINPROGRESS is used to indicate the request is + * in flight. It should be the first result value + * set after the initial -EBADR. Issue a warning + * and record an implementation error if it's + * set at any other time. + */ spin_lock_irq(&gb_operations_lock); prev = operation->errno; if (prev == -EBADR) operation->errno = result; + else + operation->errno = -EILSEQ; spin_unlock_irq(&gb_operations_lock); + WARN_ON(prev != -EBADR); - return !WARN_ON(prev != -EBADR); + return true; } - /* Trying to set final status; only the first one succeeds */ + /* + * The first result value set after a request has been sent + * will be the final result of the operation. Subsequent + * attempts to set the result are ignored. + * + * Note that -EBADR is a reserved "initial state" result + * value. Attempts to set this value result in a warning, + * and the result code is set to -EILSEQ instead. + */ + if (WARN_ON(result == -EBADR)) + result = -EILSEQ; /* Nobody should be setting -EBADR */ + spin_lock_irq(&gb_operations_lock); prev = operation->errno; if (prev == -EINPROGRESS) - operation->errno = result; + operation->errno = result; /* First and final result */ spin_unlock_irq(&gb_operations_lock); return prev == -EINPROGRESS; @@ -117,6 +143,7 @@ int gb_operation_result(struct gb_operation *operation) { int result = operation->errno; + WARN_ON(result == -EBADR); WARN_ON(result == -EINPROGRESS); return result;