Re: [lwip-users] memory leak ?

[Noam weissman]

Dear Sylvain,

All my modules are RAW API including the WEB server.

Using critical section in pin point location is not wrong. Any other 
implementation will
Have to use a more complicated queuing mechanism.

Complicated, maybe. Slower, maybe but not stupid, sorry :-)

BR,
Noam. 

-----Original Message-----
From: address@hidden [mailto:address@hidden On Behalf Of Sylvain Rochet
Sent: Thursday, June 04, 2015 3:45 PM
To: Mailing list for lwIP users
Subject: Re: [lwip-users] memory leak ?

Hello Jan,

On Thu, Jun 04, 2015 at 02:34:39PM +0200, Jan Menzel wrote:
> Hi Noam!
>       From earlier discussion on this list, I learned that for this purpose 
> one may schedule a callback into the LWIPs internal task using
> tcpip_callback() or tcpip_callback_with_blocking(). Both queue your 
> function and its arguments for execution from within the main Lwip 
> task context. I'm not sure if this is applicable here, but if so, I 
> would favour the callback solution as yours might introduce dead locks 
> in case
> tcp_sndbuf() blocks. This type of errors are comparably difficult to 
> find and likely to happen if eg. an other task is used to free buffers 
> after transmission completed.

You are right.

For future readers which might looks at this thread in the hope of getting a 
clue, please don't get fooled !, what Noam is doing is completely wrong. Adding 
a critical section and playing with thread priority this way is either 
dangerous or just stupid. (And don't tell me that it is working, I don't care 
if it -appears- to work).

OS users HAVE TO use the Netconn or Socket API if they want to call lwIP 
functions from others threads, period. RAW API is ***NOT*** thread-safe.

I repeat, RAW API is ***NOT*** thread-safe.

Sylvain

 
 
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